Add location backed system clock

This provides a permissionless way to use the location (e.g. GNSS)
provided time data for more accurate time keeping.

Test: atest LocationManagerTest#testGnssProvidedClock
Bug: 123530510
Change-Id: Ifbc45997868040abbb3e1399a8649911afb0af05

location/java/android/location/LocationTime.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.location;
+
+import android.annotation.NonNull;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+/**
+ * Data class for passing location derived time.
+ * @hide
+ */
+public final class LocationTime implements Parcelable {
+
+    private final long mTime;
+    private final long mElapsedRealtimeNanos;
+
+    public LocationTime(long time, long elapsedRealtimeNanos) {
+        mTime = time;
+        mElapsedRealtimeNanos = elapsedRealtimeNanos;
+    }
+
+    /**
+     * The current time, according to the Gnss location provider. */
+    public long getTime() {
+        return mTime;
+    }
+
+    /**
+     * The elapsed nanos since boot {@link #getTime} was computed at.
+     */
+    public long getElapsedRealtimeNanos() {
+        return mElapsedRealtimeNanos;
+    }
+
+    @Override
+    public void writeToParcel(Parcel out, int flags) {
+        out.writeLong(mTime);
+        out.writeLong(mElapsedRealtimeNanos);
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    public static final @NonNull Parcelable.Creator<LocationTime> CREATOR =
+            new Parcelable.Creator<LocationTime>() {
+                public LocationTime createFromParcel(Parcel in) {
+                    long time = in.readLong();
+                    long elapsedRealtimeNanos = in.readLong();
+                    return new LocationTime(time, elapsedRealtimeNanos);
+                }
+
+                public LocationTime[] newArray(int size) {
+                    return new LocationTime[size];
+                }
+            };
+}