From 87655fd9707857fd72f68b880155171f9165772c Mon Sep 17 00:00:00 2001
From: Neil Fuller <nfuller@google.com>
Date: Mon, 18 Oct 2021 16:50:56 +0100
Subject: [PATCH] Add a time field to GeolocationTimeZoneSuggestion

Add a time field to GeolocationTimeZoneSuggestion for use in upcoming
fallback logic. This is should help establish ordering across
different time zone detection mechanisms.

Bug: 197624972
Test: treehugger
Test: frameworks/base: atest services/tests/servicestests/src/com/android/server/timezonedetector/
Test: cts: atest hostsidetests/time/host/
Change-Id: I824679f3eca39a69d5413d365889ad8566d3e557
---
 .../GeolocationTimeZoneSuggestion.java        |  87 ++++++++++---
 .../location/ControllerEnvironmentImpl.java   |   7 ++
 .../location/ControllerImpl.java              | 110 ++++++++++------
 .../LocationTimeZoneProviderController.java   |   7 ++
 .../GeolocationTimeZoneSuggestionTest.java    |  46 ++++---
 .../TimeZoneDetectorInternalImplTest.java     |   4 +-
 .../TimeZoneDetectorServiceTest.java          |   6 +-
 .../TimeZoneDetectorStrategyImplTest.java     |  44 ++++---
 .../location/ControllerImplTest.java          | 119 ++++++++++++------
 9 files changed, 295 insertions(+), 135 deletions(-)

diff --git a/services/core/java/com/android/server/timezonedetector/GeolocationTimeZoneSuggestion.java b/services/core/java/com/android/server/timezonedetector/GeolocationTimeZoneSuggestion.java
index 1867ee207958b..3b3254985abca 100644
--- a/services/core/java/com/android/server/timezonedetector/GeolocationTimeZoneSuggestion.java
+++ b/services/core/java/com/android/server/timezonedetector/GeolocationTimeZoneSuggestion.java
@@ -16,9 +16,11 @@
 
 package com.android.server.timezonedetector;
 
+import android.annotation.ElapsedRealtimeLong;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.os.ShellCommand;
+import android.os.SystemClock;
 
 import java.io.PrintWriter;
 import java.util.ArrayList;
@@ -29,27 +31,39 @@ import java.util.Objects;
 import java.util.StringTokenizer;
 
 /**
- * A time zone suggestion from a geolocation source.
+ * A time zone suggestion from the location_time_zone_manager service to the time_zone_detector
+ * service.
  *
- * <p> Geolocation-based suggestions have the following properties:
+ * <p>Geolocation-based suggestions have the following properties:
  *
  * <ul>
+ *     <li>{@code effectiveFromElapsedMillis}: The time according to the elapsed realtime clock
+ *     after which the suggestion should be considered in effect. For example, when a location fix
+ *     used to establish the time zone is old, then the suggestion
+ *     {@code effectiveFromElapsedMillis} should reflect this and indicates the time zone that was
+ *     detected / correct at that time. The time_zone_detector is only expected to use the latest
+ *     suggestion it has received, and so later suggestions always counteract previous suggestions.
+ *     The inclusion of this information means that the time_zone_detector can take into account
+ *     ordering when comparing suggestions from different sources.
+ *     <br />Note: Because the times can be back-dated, time_zone_detector can be sent a sequence of
+ *     suggestions where the {@code effectiveFromElapsedMillis} of later suggestions is before
+ *     the {@code effectiveFromElapsedMillis} of an earlier one.</li>
  *     <li>{@code zoneIds}. When not {@code null}, {@code zoneIds} contains a list of suggested time
  *     zone IDs, e.g. ["America/Phoenix", "America/Denver"]. Usually there will be a single zoneId.
  *     When there are multiple, this indicates multiple answers are possible for the current
- *     location / accuracy, i.e. if there is a nearby time zone border. The detection logic
- *     receiving the suggestion is expected to use the first element in the absence of other
- *     information, but one of the others may be used if there is supporting evidence / preferences
- *     such as a device setting or corroborating signals from another source.
+ *     location / accuracy, e.g. if there is a nearby time zone border. The time_zone_detector is
+ *     expected to use the first element in the absence of other information, but one of the other
+ *     zone IDs may be used if there is supporting evidence / preferences such as a device setting
+ *     or corroborating signals from another source.
  *     <br />{@code zoneIds} can be empty if the current location has been determined to have no
  *     time zone. For example, oceans or disputed areas. This is considered a strong signal and the
- *     received need not look for time zone from other sources.
- *     <br />{@code zoneIds} can be {@code null} to indicate that the geolocation source has entered
- *     an "un-opinionated" state and any previous suggestion is being withdrawn. This indicates the
- *     source cannot provide a valid suggestion due to technical limitations. For example, a
- *     geolocation source may become un-opinionated if the device's location is no longer known with
- *     sufficient accuracy, or if the location is known but no time zone can be determined because
- *     no time zone mapping information is available.</li>
+ *     time_zone_detector need not look for time zone from other sources.
+ *     <br />{@code zoneIds} can be {@code null} to indicate that the location_time_zone_manager has
+ *     entered an "uncertain" state and any previous suggestion is being withdrawn. This indicates
+ *     the location_time_zone_manager cannot provide a valid suggestion. For example, the
+ *     location_time_zone_manager may become uncertain if components further downstream cannot
+ *     determine the device's location with sufficient accuracy, or if the location is known but no
+ *     time zone can be determined because no time zone mapping information is available.</li>
  *     <li>{@code debugInfo} contains debugging metadata associated with the suggestion. This is
  *     used to record why the suggestion exists and how it was obtained. This information exists
  *     only to aid in debugging and therefore is used by {@link #toString()}, but it is not for use
@@ -61,10 +75,14 @@ import java.util.StringTokenizer;
  */
 public final class GeolocationTimeZoneSuggestion {
 
+    @ElapsedRealtimeLong private final long mEffectiveFromElapsedMillis;
     @Nullable private final List<String> mZoneIds;
     @Nullable private ArrayList<String> mDebugInfo;
 
-    public GeolocationTimeZoneSuggestion(@Nullable List<String> zoneIds) {
+    private GeolocationTimeZoneSuggestion(
+            @ElapsedRealtimeLong long effectiveFromElapsedMillis,
+            @Nullable List<String> zoneIds) {
+        mEffectiveFromElapsedMillis = effectiveFromElapsedMillis;
         if (zoneIds == null) {
             // Unopinionated
             mZoneIds = null;
@@ -73,6 +91,34 @@ public final class GeolocationTimeZoneSuggestion {
         }
     }
 
+    /**
+     * Creates a "uncertain" suggestion instance.
+     */
+    @NonNull
+    public static GeolocationTimeZoneSuggestion createUncertainSuggestion(
+            @ElapsedRealtimeLong long effectiveFromElapsedMillis) {
+        return new GeolocationTimeZoneSuggestion(effectiveFromElapsedMillis, null);
+    }
+
+    /**
+     * Creates a "certain" suggestion instance.
+     */
+    @NonNull
+    public static GeolocationTimeZoneSuggestion createCertainSuggestion(
+            @ElapsedRealtimeLong long effectiveFromElapsedMillis,
+            @NonNull List<String> zoneIds) {
+        return new GeolocationTimeZoneSuggestion(effectiveFromElapsedMillis, zoneIds);
+    }
+
+    /**
+     * Returns the "effective from" time associated with the suggestion. See {@link
+     * GeolocationTimeZoneSuggestion} for details.
+     */
+    @ElapsedRealtimeLong
+    public long getEffectiveFromElapsedMillis() {
+        return mEffectiveFromElapsedMillis;
+    }
+
     /**
      * Returns the zone Ids being suggested. See {@link GeolocationTimeZoneSuggestion} for details.
      */
@@ -110,18 +156,20 @@ public final class GeolocationTimeZoneSuggestion {
         }
         GeolocationTimeZoneSuggestion
                 that = (GeolocationTimeZoneSuggestion) o;
-        return Objects.equals(mZoneIds, that.mZoneIds);
+        return mEffectiveFromElapsedMillis == that.mEffectiveFromElapsedMillis
+                && Objects.equals(mZoneIds, that.mZoneIds);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(mZoneIds);
+        return Objects.hash(mEffectiveFromElapsedMillis, mZoneIds);
     }
 
     @Override
     public String toString() {
         return "GeolocationTimeZoneSuggestion{"
-                + "mZoneIds=" + mZoneIds
+                + "mEffectiveFromElapsedMillis=" + mEffectiveFromElapsedMillis
+                + ", mZoneIds=" + mZoneIds
                 + ", mDebugInfo=" + mDebugInfo
                 + '}';
     }
@@ -141,8 +189,11 @@ public final class GeolocationTimeZoneSuggestion {
                 }
             }
         }
+
+        long elapsedRealtimeMillis = SystemClock.elapsedRealtime();
         List<String> zoneIds = parseZoneIdsArg(zoneIdsString);
-        GeolocationTimeZoneSuggestion suggestion = new GeolocationTimeZoneSuggestion(zoneIds);
+        GeolocationTimeZoneSuggestion suggestion =
+                new GeolocationTimeZoneSuggestion(elapsedRealtimeMillis, zoneIds);
         suggestion.addDebugInfo("Command line injection");
         return suggestion;
     }
diff --git a/services/core/java/com/android/server/timezonedetector/location/ControllerEnvironmentImpl.java b/services/core/java/com/android/server/timezonedetector/location/ControllerEnvironmentImpl.java
index 551a05950b27c..20fb61ddf83d1 100644
--- a/services/core/java/com/android/server/timezonedetector/location/ControllerEnvironmentImpl.java
+++ b/services/core/java/com/android/server/timezonedetector/location/ControllerEnvironmentImpl.java
@@ -16,7 +16,9 @@
 
 package com.android.server.timezonedetector.location;
 
+import android.annotation.ElapsedRealtimeLong;
 import android.annotation.NonNull;
+import android.os.SystemClock;
 
 import com.android.server.LocalServices;
 import com.android.server.timezonedetector.ConfigurationChangeListener;
@@ -83,4 +85,9 @@ class ControllerEnvironmentImpl extends LocationTimeZoneProviderController.Envir
     Duration getProviderEventFilteringAgeThreshold() {
         return mServiceConfigAccessor.getLocationTimeZoneProviderEventFilteringAgeThreshold();
     }
+
+    @Override
+    @ElapsedRealtimeLong long elapsedRealtimeMillis() {
+        return SystemClock.elapsedRealtime();
+    }
 }
diff --git a/services/core/java/com/android/server/timezonedetector/location/ControllerImpl.java b/services/core/java/com/android/server/timezonedetector/location/ControllerImpl.java
index 1d58cea1be3d5..466a0391746f7 100644
--- a/services/core/java/com/android/server/timezonedetector/location/ControllerImpl.java
+++ b/services/core/java/com/android/server/timezonedetector/location/ControllerImpl.java
@@ -31,10 +31,11 @@ import static com.android.server.timezonedetector.location.LocationTimeZoneProvi
 import static com.android.server.timezonedetector.location.LocationTimeZoneProvider.ProviderState.PROVIDER_STATE_STOPPED;
 
 import android.annotation.DurationMillisLong;
-import android.annotation.IntRange;
+import android.annotation.ElapsedRealtimeLong;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.service.timezone.TimeZoneProviderEvent;
+import android.service.timezone.TimeZoneProviderSuggestion;
 import android.util.IndentingPrintWriter;
 
 import com.android.internal.annotations.GuardedBy;
@@ -43,7 +44,6 @@ import com.android.server.timezonedetector.GeolocationTimeZoneSuggestion;
 import com.android.server.timezonedetector.location.ThreadingDomain.SingleRunnableQueue;
 
 import java.time.Duration;
-import java.util.List;
 import java.util.Objects;
 
 /**
@@ -184,7 +184,7 @@ class ControllerImpl extends LocationTimeZoneProviderController {
         // re-started).
         if (mLastSuggestion != null && mLastSuggestion.getZoneIds() != null) {
             GeolocationTimeZoneSuggestion suggestion = createUncertainSuggestion(
-                    "Providers are stopping");
+                    mEnvironment.elapsedRealtimeMillis(), "Providers are stopping");
             makeSuggestion(suggestion);
         }
     }
@@ -272,6 +272,7 @@ class ControllerImpl extends LocationTimeZoneProviderController {
                     // If both providers are {perm failed} then the controller immediately
                     // becomes uncertain.
                     GeolocationTimeZoneSuggestion suggestion = createUncertainSuggestion(
+                            mEnvironment.elapsedRealtimeMillis(),
                             "Providers are failed:"
                                     + " primary=" + mPrimaryProvider.getCurrentState()
                                     + " secondary=" + mPrimaryProvider.getCurrentState());
@@ -410,6 +411,7 @@ class ControllerImpl extends LocationTimeZoneProviderController {
             // If both providers are now terminated, then a suggestion must be sent informing the
             // time zone detector that there are no further updates coming in future.
             GeolocationTimeZoneSuggestion suggestion = createUncertainSuggestion(
+                    mEnvironment.elapsedRealtimeMillis(),
                     "Both providers are terminated:"
                             + " primary=" + primaryCurrentState.provider
                             + ", secondary=" + secondaryCurrentState.provider);
@@ -432,8 +434,9 @@ class ControllerImpl extends LocationTimeZoneProviderController {
             // the loss of a binder-based provider, or initialization took too long. This is treated
             // the same as explicit uncertainty, i.e. where the provider has explicitly told this
             // process it is uncertain.
-            handleProviderUncertainty(provider, "provider=" + provider
-                    + ", implicit uncertainty, event=null");
+            long uncertaintyStartedElapsedMillis = mEnvironment.elapsedRealtimeMillis();
+            handleProviderUncertainty(provider, uncertaintyStartedElapsedMillis,
+                    "provider=" + provider + ", implicit uncertainty, event=null");
             return;
         }
 
@@ -448,18 +451,17 @@ class ControllerImpl extends LocationTimeZoneProviderController {
         switch (event.getType()) {
             case EVENT_TYPE_PERMANENT_FAILURE: {
                 // This shouldn't happen. A provider cannot be started and have this event type.
-                warnLog("Provider=" + provider
-                        + " is started, but event suggests it shouldn't be");
+                warnLog("Provider=" + provider + " is started, but event suggests it shouldn't be");
                 break;
             }
             case EVENT_TYPE_UNCERTAIN: {
-                handleProviderUncertainty(provider, "provider=" + provider
-                        + ", explicit uncertainty. event=" + event);
+                long uncertaintyStartedElapsedMillis = event.getCreationElapsedMillis();
+                handleProviderUncertainty(provider, uncertaintyStartedElapsedMillis,
+                        "provider=" + provider + ", explicit uncertainty. event=" + event);
                 break;
             }
             case EVENT_TYPE_SUGGESTION: {
-                handleProviderSuggestion(provider, event.getSuggestion().getTimeZoneIds(),
-                        "Event received provider=" + provider + ", event=" + event);
+                handleProviderSuggestion(provider, event);
                 break;
             }
             default: {
@@ -475,8 +477,8 @@ class ControllerImpl extends LocationTimeZoneProviderController {
     @GuardedBy("mSharedLock")
     private void handleProviderSuggestion(
             @NonNull LocationTimeZoneProvider provider,
-            @Nullable List<String> timeZoneIds,
-            @NonNull String reason) {
+            @NonNull TimeZoneProviderEvent providerEvent) {
+
         // By definition, the controller is now certain.
         cancelUncertaintyTimeout();
 
@@ -484,10 +486,25 @@ class ControllerImpl extends LocationTimeZoneProviderController {
             stopProviderIfStarted(mSecondaryProvider);
         }
 
-        GeolocationTimeZoneSuggestion suggestion = new GeolocationTimeZoneSuggestion(timeZoneIds);
-        suggestion.addDebugInfo(reason);
-        // Rely on the receiver to dedupe suggestions. It is better to over-communicate.
-        makeSuggestion(suggestion);
+        TimeZoneProviderSuggestion providerSuggestion = providerEvent.getSuggestion();
+
+        // For the suggestion's effectiveFromElapsedMillis, use the time embedded in the provider's
+        // suggestion (which indicates the time when the provider detected the location used to
+        // establish the time zone).
+        //
+        // An alternative would be to use the current time or the providerEvent creation time, but
+        // this would hinder the ability for the time_zone_detector to judge which suggestions are
+        // based on newer information when comparing suggestions between different sources.
+        long effectiveFromElapsedMillis = providerSuggestion.getElapsedRealtimeMillis();
+        GeolocationTimeZoneSuggestion geoSuggestion =
+                GeolocationTimeZoneSuggestion.createCertainSuggestion(
+                        effectiveFromElapsedMillis, providerSuggestion.getTimeZoneIds());
+
+        String debugInfo = "Event received provider=" + provider
+                + ", providerEvent=" + providerEvent
+                + ", suggestionCreationTime=" + mEnvironment.elapsedRealtimeMillis();
+        geoSuggestion.addDebugInfo(debugInfo);
+        makeSuggestion(geoSuggestion);
     }
 
     @Override
@@ -551,7 +568,9 @@ class ControllerImpl extends LocationTimeZoneProviderController {
      */
     @GuardedBy("mSharedLock")
     void handleProviderUncertainty(
-            @NonNull LocationTimeZoneProvider provider, @NonNull String reason) {
+            @NonNull LocationTimeZoneProvider provider,
+            @ElapsedRealtimeLong long uncertaintyStartedElapsedMillis,
+            @NonNull String reason) {
         Objects.requireNonNull(provider);
 
         // Start the uncertainty timeout if needed to ensure the controller will eventually make an
@@ -559,9 +578,11 @@ class ControllerImpl extends LocationTimeZoneProviderController {
         if (!mUncertaintyTimeoutQueue.hasQueued()) {
             debugLog("Starting uncertainty timeout: reason=" + reason);
 
-            Duration delay = mEnvironment.getUncertaintyDelay();
-            mUncertaintyTimeoutQueue.runDelayed(() -> onProviderUncertaintyTimeout(provider),
-                    delay.toMillis());
+            Duration uncertaintyDelay = mEnvironment.getUncertaintyDelay();
+            mUncertaintyTimeoutQueue.runDelayed(
+                    () -> onProviderUncertaintyTimeout(
+                            provider, uncertaintyStartedElapsedMillis, uncertaintyDelay),
+                    uncertaintyDelay.toMillis());
         }
 
         if (provider == mPrimaryProvider) {
@@ -573,21 +594,45 @@ class ControllerImpl extends LocationTimeZoneProviderController {
         }
     }
 
-    private void onProviderUncertaintyTimeout(@NonNull LocationTimeZoneProvider provider) {
+    private void onProviderUncertaintyTimeout(
+            @NonNull LocationTimeZoneProvider provider,
+            @ElapsedRealtimeLong long uncertaintyStartedElapsedMillis,
+            @NonNull Duration uncertaintyDelay) {
         mThreadingDomain.assertCurrentThread();
 
         synchronized (mSharedLock) {
+            long afterUncertaintyTimeoutElapsedMillis = mEnvironment.elapsedRealtimeMillis();
+
+            // For the effectiveFromElapsedMillis suggestion property, use the
+            // uncertaintyStartedElapsedMillis. This is the time when the provider first reported
+            // uncertainty, i.e. before the uncertainty timeout.
+            //
+            // afterUncertaintyTimeoutElapsedMillis could be used instead, which is the time when
+            // the location_time_zone_manager finally confirms that the time zone was uncertain,
+            // but the suggestion property allows the information to be back-dated, which should
+            // help when comparing suggestions from different sources.
             GeolocationTimeZoneSuggestion suggestion = createUncertainSuggestion(
+                    uncertaintyStartedElapsedMillis,
                     "Uncertainty timeout triggered for " + provider.getName() + ":"
                             + " primary=" + mPrimaryProvider
-                            + ", secondary=" + mSecondaryProvider);
+                            + ", secondary=" + mSecondaryProvider
+                            + ", uncertaintyStarted="
+                            + Duration.ofMillis(uncertaintyStartedElapsedMillis)
+                            + ", afterUncertaintyTimeout="
+                            + Duration.ofMillis(afterUncertaintyTimeoutElapsedMillis)
+                            + ", uncertaintyDelay=" + uncertaintyDelay
+            );
             makeSuggestion(suggestion);
         }
     }
 
     @NonNull
-    private static GeolocationTimeZoneSuggestion createUncertainSuggestion(@NonNull String reason) {
-        GeolocationTimeZoneSuggestion suggestion = new GeolocationTimeZoneSuggestion(null);
+    private static GeolocationTimeZoneSuggestion createUncertainSuggestion(
+            @ElapsedRealtimeLong long effectiveFromElapsedMillis,
+            @NonNull String reason) {
+        GeolocationTimeZoneSuggestion suggestion =
+                GeolocationTimeZoneSuggestion.createUncertainSuggestion(
+                        effectiveFromElapsedMillis);
         suggestion.addDebugInfo(reason);
         return suggestion;
     }
@@ -622,19 +667,4 @@ class ControllerImpl extends LocationTimeZoneProviderController {
             return builder.build();
         }
     }
-
-    @Nullable
-    private LocationTimeZoneProvider getLocationTimeZoneProvider(
-            @IntRange(from = 0, to = 1) int providerIndex) {
-        LocationTimeZoneProvider targetProvider;
-        if (providerIndex == 0) {
-            targetProvider = mPrimaryProvider;
-        } else if (providerIndex == 1) {
-            targetProvider = mSecondaryProvider;
-        } else {
-            warnLog("Bad providerIndex=" + providerIndex);
-            targetProvider = null;
-        }
-        return targetProvider;
-    }
 }
diff --git a/services/core/java/com/android/server/timezonedetector/location/LocationTimeZoneProviderController.java b/services/core/java/com/android/server/timezonedetector/location/LocationTimeZoneProviderController.java
index d2fd9a9f307e3..fdb9c14e7c597 100644
--- a/services/core/java/com/android/server/timezonedetector/location/LocationTimeZoneProviderController.java
+++ b/services/core/java/com/android/server/timezonedetector/location/LocationTimeZoneProviderController.java
@@ -17,6 +17,7 @@
 package com.android.server.timezonedetector.location;
 
 import android.annotation.DurationMillisLong;
+import android.annotation.ElapsedRealtimeLong;
 import android.annotation.NonNull;
 import android.os.Handler;
 
@@ -140,6 +141,12 @@ abstract class LocationTimeZoneProviderController implements Dumpable {
          * passed on.
          */
         abstract Duration getUncertaintyDelay();
+
+        /**
+         * Returns the elapsed realtime as millis, the same as {@link
+         * android.os.SystemClock#elapsedRealtime()}.
+         */
+        abstract @ElapsedRealtimeLong long elapsedRealtimeMillis();
     }
 
     /**
diff --git a/services/tests/servicestests/src/com/android/server/timezonedetector/GeolocationTimeZoneSuggestionTest.java b/services/tests/servicestests/src/com/android/server/timezonedetector/GeolocationTimeZoneSuggestionTest.java
index 5870a70c49ae9..79f8b0e8d4c8d 100644
--- a/services/tests/servicestests/src/com/android/server/timezonedetector/GeolocationTimeZoneSuggestionTest.java
+++ b/services/tests/servicestests/src/com/android/server/timezonedetector/GeolocationTimeZoneSuggestionTest.java
@@ -34,26 +34,36 @@ public class GeolocationTimeZoneSuggestionTest {
 
     @Test
     public void testEquals() {
-        GeolocationTimeZoneSuggestion one = new GeolocationTimeZoneSuggestion(ARBITRARY_ZONE_IDS1);
-        assertEquals(one, one);
+        long time1 = 1111L;
+        GeolocationTimeZoneSuggestion certain1v1 =
+                GeolocationTimeZoneSuggestion.createCertainSuggestion(time1, ARBITRARY_ZONE_IDS1);
+        assertEquals(certain1v1, certain1v1);
 
-        GeolocationTimeZoneSuggestion two = new GeolocationTimeZoneSuggestion(ARBITRARY_ZONE_IDS1);
-        assertEquals(one, two);
-        assertEquals(two, one);
-
-        GeolocationTimeZoneSuggestion nullZone = new GeolocationTimeZoneSuggestion(null);
-        assertNotEquals(one, nullZone);
-        assertNotEquals(nullZone, one);
-        assertEquals(nullZone, nullZone);
-
-        GeolocationTimeZoneSuggestion three =
-                new GeolocationTimeZoneSuggestion(ARBITRARY_ZONE_IDS2);
-        assertNotEquals(one, three);
-        assertNotEquals(three, one);
+        GeolocationTimeZoneSuggestion certain1v2 =
+                GeolocationTimeZoneSuggestion.createCertainSuggestion(time1, ARBITRARY_ZONE_IDS1);
+        assertEquals(certain1v1, certain1v2);
+        assertEquals(certain1v2, certain1v1);
 
         // DebugInfo must not be considered in equals().
-        one.addDebugInfo("Debug info 1");
-        two.addDebugInfo("Debug info 2");
-        assertEquals(one, two);
+        certain1v1.addDebugInfo("Debug info 1");
+        certain1v2.addDebugInfo("Debug info 2");
+        assertEquals(certain1v1, certain1v2);
+
+        long time2 = 2222L;
+        GeolocationTimeZoneSuggestion certain2 =
+                GeolocationTimeZoneSuggestion.createCertainSuggestion(time2, ARBITRARY_ZONE_IDS1);
+        assertNotEquals(certain1v1, certain2);
+        assertNotEquals(certain2, certain1v1);
+
+        GeolocationTimeZoneSuggestion uncertain =
+                GeolocationTimeZoneSuggestion.createUncertainSuggestion(time1);
+        assertNotEquals(certain1v1, uncertain);
+        assertNotEquals(uncertain, certain1v1);
+        assertEquals(uncertain, uncertain);
+
+        GeolocationTimeZoneSuggestion certain3 =
+                GeolocationTimeZoneSuggestion.createCertainSuggestion(time1, ARBITRARY_ZONE_IDS2);
+        assertNotEquals(certain1v1, certain3);
+        assertNotEquals(certain3, certain1v1);
     }
 }
diff --git a/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorInternalImplTest.java b/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorInternalImplTest.java
index 918babca677ed..586462006ee28 100644
--- a/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorInternalImplTest.java
+++ b/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorInternalImplTest.java
@@ -35,6 +35,7 @@ import java.util.List;
 @RunWith(AndroidJUnit4.class)
 public class TimeZoneDetectorInternalImplTest {
 
+    private static final long ARBITRARY_ELAPSED_REALTIME_MILLIS = 1234L;
     private static final List<String> ARBITRARY_ZONE_IDS = Arrays.asList("TestZoneId");
 
     private Context mMockContext;
@@ -99,6 +100,7 @@ public class TimeZoneDetectorInternalImplTest {
     }
 
     private static GeolocationTimeZoneSuggestion createGeolocationTimeZoneSuggestion() {
-        return new GeolocationTimeZoneSuggestion(ARBITRARY_ZONE_IDS);
+        return GeolocationTimeZoneSuggestion.createCertainSuggestion(
+                ARBITRARY_ELAPSED_REALTIME_MILLIS, ARBITRARY_ZONE_IDS);
     }
 }
diff --git a/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorServiceTest.java b/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorServiceTest.java
index 28838ae14f2f2..773abf86e18ab 100644
--- a/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorServiceTest.java
@@ -50,11 +50,14 @@ import org.junit.runner.RunWith;
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.util.Arrays;
+import java.util.List;
 
 @RunWith(AndroidJUnit4.class)
 public class TimeZoneDetectorServiceTest {
 
     private static final int ARBITRARY_USER_ID = 9999;
+    private static final List<String> ARBITRARY_TIME_ZONE_IDS = Arrays.asList("TestZoneId");
+    private static final long ARBITRARY_ELAPSED_REALTIME_MILLIS = 1234L;
 
     private Context mMockContext;
     private FakeTimeZoneDetectorStrategy mFakeTimeZoneDetectorStrategy;
@@ -374,7 +377,8 @@ public class TimeZoneDetectorServiceTest {
     }
 
     private static GeolocationTimeZoneSuggestion createGeolocationTimeZoneSuggestion() {
-        return new GeolocationTimeZoneSuggestion(Arrays.asList("TestZoneId"));
+        return GeolocationTimeZoneSuggestion.createCertainSuggestion(
+                ARBITRARY_ELAPSED_REALTIME_MILLIS, ARBITRARY_TIME_ZONE_IDS);
     }
 
     private static ManualTimeZoneSuggestion createManualTimeZoneSuggestion() {
diff --git a/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorStrategyImplTest.java b/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorStrategyImplTest.java
index 331f76cf7dc26..e2e875507c93a 100644
--- a/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorStrategyImplTest.java
+++ b/services/tests/servicestests/src/com/android/server/timezonedetector/TimeZoneDetectorStrategyImplTest.java
@@ -33,10 +33,13 @@ import static com.android.server.timezonedetector.TimeZoneDetectorStrategyImpl.T
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
+import android.annotation.ElapsedRealtimeLong;
+import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.UserIdInt;
 import android.app.time.TimeZoneConfiguration;
@@ -171,6 +174,8 @@ public class TimeZoneDetectorStrategyImplTest {
     private FakeEnvironment mFakeEnvironment;
     private MockConfigChangeListener mMockConfigChangeListener;
 
+    // A fake source of time for suggestions. This will typically be incremented after every use.
+    @ElapsedRealtimeLong private long mElapsedRealtimeMillis;
 
     @Before
     public void setUp() {
@@ -487,7 +492,7 @@ public class TimeZoneDetectorStrategyImplTest {
          */
 
         // Each test case will have the same or lower score than the last.
-        List<TelephonyTestCase> descendingCasesByScore = list(TELEPHONY_TEST_CASES);
+        List<TelephonyTestCase> descendingCasesByScore = Arrays.asList(TELEPHONY_TEST_CASES);
         Collections.reverse(descendingCasesByScore);
 
         for (TelephonyTestCase testCase : descendingCasesByScore) {
@@ -750,7 +755,7 @@ public class TimeZoneDetectorStrategyImplTest {
         Script script = new Script().initializeConfig(CONFIG_INT_AUTO_ENABLED_GEO_ENABLED)
                 .initializeTimeZoneSetting(ARBITRARY_TIME_ZONE_ID);
 
-        GeolocationTimeZoneSuggestion uncertainSuggestion = createUncertainGeoLocationSuggestion();
+        GeolocationTimeZoneSuggestion uncertainSuggestion = createUncertainGeolocationSuggestion();
 
         script.simulateGeolocationTimeZoneSuggestion(uncertainSuggestion)
                 .verifyTimeZoneNotChanged();
@@ -766,7 +771,7 @@ public class TimeZoneDetectorStrategyImplTest {
                 .initializeConfig(CONFIG_INT_AUTO_ENABLED_GEO_ENABLED)
                 .initializeTimeZoneSetting(ARBITRARY_TIME_ZONE_ID);
 
-        GeolocationTimeZoneSuggestion noZonesSuggestion = createGeoLocationSuggestion(list());
+        GeolocationTimeZoneSuggestion noZonesSuggestion = createCertainGeolocationSuggestion();
 
         script.simulateGeolocationTimeZoneSuggestion(noZonesSuggestion)
                 .verifyTimeZoneNotChanged();
@@ -778,7 +783,7 @@ public class TimeZoneDetectorStrategyImplTest {
     @Test
     public void testGeoSuggestion_oneZone() {
         GeolocationTimeZoneSuggestion suggestion =
-                createGeoLocationSuggestion(list("Europe/London"));
+                createCertainGeolocationSuggestion("Europe/London");
 
         Script script = new Script()
                 .initializeConfig(CONFIG_INT_AUTO_ENABLED_GEO_ENABLED)
@@ -799,11 +804,11 @@ public class TimeZoneDetectorStrategyImplTest {
     @Test
     public void testGeoSuggestion_multiZone() {
         GeolocationTimeZoneSuggestion londonOnlySuggestion =
-                createGeoLocationSuggestion(list("Europe/London"));
+                createCertainGeolocationSuggestion("Europe/London");
         GeolocationTimeZoneSuggestion londonOrParisSuggestion =
-                createGeoLocationSuggestion(list("Europe/Paris", "Europe/London"));
+                createCertainGeolocationSuggestion("Europe/Paris", "Europe/London");
         GeolocationTimeZoneSuggestion parisOnlySuggestion =
-                createGeoLocationSuggestion(list("Europe/Paris"));
+                createCertainGeolocationSuggestion("Europe/Paris");
 
         Script script = new Script()
                 .initializeConfig(CONFIG_INT_AUTO_ENABLED_GEO_ENABLED)
@@ -836,7 +841,7 @@ public class TimeZoneDetectorStrategyImplTest {
     @Test
     public void testGeoSuggestion_togglingGeoDetectionClearsLastSuggestion() {
         GeolocationTimeZoneSuggestion suggestion =
-                createGeoLocationSuggestion(list("Europe/London"));
+                createCertainGeolocationSuggestion("Europe/London");
 
         Script script = new Script()
                 .initializeConfig(CONFIG_INT_AUTO_ENABLED_GEO_ENABLED)
@@ -863,7 +868,7 @@ public class TimeZoneDetectorStrategyImplTest {
     @Test
     public void testChangingGeoDetectionEnabled() {
         GeolocationTimeZoneSuggestion geolocationSuggestion =
-                createGeoLocationSuggestion(list("Europe/London"));
+                createCertainGeolocationSuggestion("Europe/London");
         TelephonyTimeZoneSuggestion telephonySuggestion = createTelephonySuggestion(
                 SLOT_INDEX1, MATCH_TYPE_NETWORK_COUNTRY_AND_OFFSET, QUALITY_SINGLE_ZONE,
                 "Europe/Paris");
@@ -960,7 +965,7 @@ public class TimeZoneDetectorStrategyImplTest {
                 createTelephonySuggestion(0 /* slotIndex */, MATCH_TYPE_NETWORK_COUNTRY_ONLY,
                         QUALITY_SINGLE_ZONE, "Zone2");
         GeolocationTimeZoneSuggestion geolocationTimeZoneSuggestion =
-                createGeoLocationSuggestion(Arrays.asList("Zone3", "Zone2"));
+                createCertainGeolocationSuggestion("Zone3", "Zone2");
         script.simulateTelephonyTimeZoneSuggestion(telephonySuggestion)
                 .verifyTimeZoneNotChanged()
                 .simulateGeolocationTimeZoneSuggestion(geolocationTimeZoneSuggestion)
@@ -1052,13 +1057,18 @@ public class TimeZoneDetectorStrategyImplTest {
         return new TelephonyTimeZoneSuggestion.Builder(SLOT_INDEX2).build();
     }
 
-    private static GeolocationTimeZoneSuggestion createUncertainGeoLocationSuggestion() {
-        return createGeoLocationSuggestion(null);
+    private GeolocationTimeZoneSuggestion createUncertainGeolocationSuggestion() {
+        return GeolocationTimeZoneSuggestion.createCertainSuggestion(
+                mElapsedRealtimeMillis++, null);
     }
 
-    private static GeolocationTimeZoneSuggestion createGeoLocationSuggestion(
-            @Nullable List<String> zoneIds) {
-        GeolocationTimeZoneSuggestion suggestion = new GeolocationTimeZoneSuggestion(zoneIds);
+    private GeolocationTimeZoneSuggestion createCertainGeolocationSuggestion(
+            @NonNull String... zoneIds) {
+        assertNotNull(zoneIds);
+
+        GeolocationTimeZoneSuggestion suggestion =
+                GeolocationTimeZoneSuggestion.createCertainSuggestion(
+                        mElapsedRealtimeMillis++, Arrays.asList(zoneIds));
         suggestion.addDebugInfo("Test suggestion");
         return suggestion;
     }
@@ -1321,8 +1331,4 @@ public class TimeZoneDetectorStrategyImplTest {
             mOnChangeCalled = false;
         }
     }
-
-    private static <T> List<T> list(T... values) {
-        return Arrays.asList(values);
-    }
 }
diff --git a/services/tests/servicestests/src/com/android/server/timezonedetector/location/ControllerImplTest.java b/services/tests/servicestests/src/com/android/server/timezonedetector/location/ControllerImplTest.java
index 27d95461ee618..7d6772ef7bd01 100644
--- a/services/tests/servicestests/src/com/android/server/timezonedetector/location/ControllerImplTest.java
+++ b/services/tests/servicestests/src/com/android/server/timezonedetector/location/ControllerImplTest.java
@@ -33,8 +33,10 @@ import static org.junit.Assert.fail;
 
 import static java.util.Arrays.asList;
 
+import android.annotation.ElapsedRealtimeLong;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
+import android.os.SystemClock;
 import android.platform.test.annotations.Presubmit;
 import android.service.timezone.TimeZoneProviderEvent;
 import android.service.timezone.TimeZoneProviderSuggestion;
@@ -287,8 +289,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
     }
 
@@ -326,8 +328,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
     }
 
@@ -366,8 +368,8 @@ public class ControllerImplTest {
                 PROVIDER_STATE_STARTED_UNCERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
     }
 
@@ -395,8 +397,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // A second, identical event should not cause another suggestion.
@@ -416,8 +418,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
     }
 
@@ -456,8 +458,8 @@ public class ControllerImplTest {
                 PROVIDER_STATE_STARTED_UNCERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // A second, identical event should not cause another suggestion.
@@ -479,8 +481,8 @@ public class ControllerImplTest {
                 PROVIDER_STATE_STARTED_UNCERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
     }
 
@@ -508,8 +510,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // Simulate an uncertain event being received from the primary provider. This should not
@@ -535,8 +537,8 @@ public class ControllerImplTest {
                 PROVIDER_STATE_STARTED_UNCERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // Simulate an uncertain event being received from the secondary provider. This should not
@@ -560,7 +562,8 @@ public class ControllerImplTest {
                 PROVIDER_STATE_STARTED_UNCERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_UNCERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
-        mTestCallback.assertUncertainSuggestionMadeAndCommit();
+        mTestCallback.assertUncertainSuggestionMadeFromEventAndCommit(
+                USER1_UNCERTAIN_LOCATION_TIME_ZONE_EVENT);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
     }
 
@@ -588,8 +591,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // Uncertainty should not cause a suggestion to be made straight away, but the uncertainty
@@ -613,8 +616,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
     }
 
@@ -682,8 +685,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // Now signal a config change so that geo detection is disabled.
@@ -723,8 +726,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // Simulate the user change (but geo detection still enabled).
@@ -789,8 +792,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertIsPermFailedAndCommit();
         mTestSecondaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // Simulate uncertainty from the secondary.
@@ -896,8 +899,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsPermFailedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT2);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // Simulate uncertainty from the primary. The secondary cannot be started.
@@ -1098,8 +1101,8 @@ public class ControllerImplTest {
         mTestPrimaryLocationTimeZoneProvider.assertStateEnumAndConfigAndCommit(
                 PROVIDER_STATE_STARTED_CERTAIN, USER1_CONFIG_GEO_DETECTION_ENABLED);
         mTestSecondaryLocationTimeZoneProvider.assertIsStoppedAndCommit();
-        mTestCallback.assertSuggestionMadeAndCommit(
-                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1.getSuggestion().getTimeZoneIds());
+        mTestCallback.assertCertainSuggestionMadeFromEventAndCommit(
+                USER1_SUCCESS_LOCATION_TIME_ZONE_EVENT1);
         assertFalse(controllerImpl.isUncertaintyTimeoutSet());
 
         // Trigger destroy().
@@ -1186,6 +1189,13 @@ public class ControllerImplTest {
             return UNCERTAINTY_DELAY;
         }
 
+        @Override
+        long elapsedRealtimeMillis() {
+            // The properties of the real clock will also work for tests, i.e. it doesn't go
+            // backwards.
+            return SystemClock.elapsedRealtime();
+        }
+
         void simulateConfigChange(ConfigurationInternal newConfig) {
             ConfigurationInternal oldConfig = mConfigurationInternal;
             mConfigurationInternal = Objects.requireNonNull(newConfig);
@@ -1209,19 +1219,52 @@ public class ControllerImplTest {
             mLatestSuggestion.set(suggestion);
         }
 
-        void assertSuggestionMadeAndCommit(@Nullable List<String> expectedZoneIds) {
-            mLatestSuggestion.assertHasBeenSet();
-            assertEquals(expectedZoneIds, mLatestSuggestion.getLatest().getZoneIds());
-            mLatestSuggestion.commitLatest();
+        void assertCertainSuggestionMadeFromEventAndCommit(TimeZoneProviderEvent event) {
+            // Test coding error if this fails.
+            assertEquals(TimeZoneProviderEvent.EVENT_TYPE_SUGGESTION, event.getType());
+
+            TimeZoneProviderSuggestion suggestion = event.getSuggestion();
+            assertSuggestionMadeAndCommit(
+                    suggestion.getElapsedRealtimeMillis(),
+                    suggestion.getTimeZoneIds());
         }
 
         void assertNoSuggestionMade() {
             mLatestSuggestion.assertHasNotBeenSet();
         }
 
+        /** Asserts that an uncertain suggestion has been made from the supplied event. */
+        void assertUncertainSuggestionMadeFromEventAndCommit(TimeZoneProviderEvent event) {
+            // Test coding error if this fails.
+            assertEquals(TimeZoneProviderEvent.EVENT_TYPE_UNCERTAIN, event.getType());
+
+            assertSuggestionMadeAndCommit(event.getCreationElapsedMillis(), null);
+        }
+
+        /**
+         * Asserts that an uncertain suggestion has been made.
+         * Ignores the suggestion's effectiveFromElapsedMillis.
+         */
         void assertUncertainSuggestionMadeAndCommit() {
             // An "uncertain" suggestion has null time zone IDs.
-            assertSuggestionMadeAndCommit(null);
+            assertSuggestionMadeAndCommit(null, null);
+        }
+
+        /**
+         * Asserts that a suggestion has been made and some properties of that suggestion.
+         * When expectedEffectiveFromElapsedMillis is null then its value isn't checked.
+         */
+        private void assertSuggestionMadeAndCommit(
+                @Nullable @ElapsedRealtimeLong Long expectedEffectiveFromElapsedMillis,
+                @Nullable List<String> expectedZoneIds) {
+            mLatestSuggestion.assertHasBeenSet();
+            if (expectedEffectiveFromElapsedMillis != null) {
+                assertEquals(
+                        expectedEffectiveFromElapsedMillis.longValue(),
+                        mLatestSuggestion.getLatest().getEffectiveFromElapsedMillis());
+            }
+            assertEquals(expectedZoneIds, mLatestSuggestion.getLatest().getZoneIds());
+            mLatestSuggestion.commitLatest();
         }
     }