Update AMS to wait for network state update if requested by the main thread.

Bug: 27803922
Test: runtest -c com.android.server.am.ActivityManagerServiceTest frameworks-services
      runtest -c com.android.server.am.ActivityManagerInternalTest frameworks-services
      cts-tradefed run singleCommand cts-dev --module CtsHostsideNetworkTests
      and manual
Change-Id: I7d1052b9941c1fae51ff8ab1c9b89dca3919ccd2

core/java/android/app/ActivityThread.java

@@ -204,6 +204,22 @@ public final class ActivityThread {
     // Whether to invoke an activity callback after delivering new configuration.
     private static final boolean REPORT_TO_ACTIVITY = true;
 
+    /**
+     * Denotes an invalid sequence number corresponding to a process state change.
+     */
+    public static final long INVALID_PROC_STATE_SEQ = -1;
+
+    private final Object mNetworkPolicyLock = new Object();
+
+    /**
+     * Denotes the sequence number of the process state change for which the main thread needs
+     * to block until the network rules are updated for it.
+     *
+     * Value of {@link #INVALID_PROC_STATE_SEQ} indicates there is no need for blocking.
+     */
+    @GuardedBy("mNetworkPolicyLock")
+    private long mNetworkBlockSeq = INVALID_PROC_STATE_SEQ;
+
     private ContextImpl mSystemContext;
 
     static volatile IPackageManager sPackageManager;
@@ -1324,6 +1340,18 @@ public final class ActivityThread {
             }
         }
 
+        /**
+         * Updates {@link #mNetworkBlockSeq}. This is used by ActivityManagerService to inform
+         * the main thread that it needs to wait for the network rules to get updated before
+         * launching an activity.
+         */
+        @Override
+        public void setNetworkBlockSeq(long procStateSeq) {
+            synchronized (mNetworkPolicyLock) {
+                mNetworkBlockSeq = procStateSeq;
+            }
+        }
+
         @Override
         public void scheduleInstallProvider(ProviderInfo provider) {
             sendMessage(H.INSTALL_PROVIDER, provider);
@@ -2698,6 +2726,7 @@ public final class ActivityThread {
                     activity.mIntent = customIntent;
                 }
                 r.lastNonConfigurationInstances = null;
+                checkAndBlockForNetworkAccess();
                 activity.mStartedActivity = false;
                 int theme = r.activityInfo.getThemeResource();
                 if (theme != 0) {
@@ -2764,6 +2793,22 @@ public final class ActivityThread {
         return activity;
     }
 
+    /**
+     * Checks if {@link #mNetworkBlockSeq} is {@link #INVALID_PROC_STATE_SEQ} and if so, returns
+     * immediately. Otherwise, makes a blocking call to ActivityManagerService to wait for the
+     * network rules to get updated.
+     */
+    private void checkAndBlockForNetworkAccess() {
+        synchronized (mNetworkPolicyLock) {
+            if (mNetworkBlockSeq != INVALID_PROC_STATE_SEQ) {
+                try {
+                    ActivityManager.getService().waitForNetworkStateUpdate(mNetworkBlockSeq);
+                    mNetworkBlockSeq = INVALID_PROC_STATE_SEQ;
+                } catch (RemoteException ignored) {}
+            }
+        }
+    }
+
     private ContextImpl createBaseContextForActivity(ActivityClientRecord r) {
         final int displayId;
         try {

core/java/android/app/IActivityManager.aidl

@@ -607,6 +607,8 @@ interface IActivityManager {
     void scheduleApplicationInfoChanged(in List<String> packageNames, int userId);
     void setPersistentVrThread(int tid);
 
+    void waitForNetworkStateUpdate(long procStateSeq);
+
     // WARNING: when these transactions are updated, check if they are any callers on the native
     // side. If so, make sure they are using the correct transaction ids and arguments.
     // If a transaction which will also be used on the native side is being inserted, add it

core/java/android/app/IApplicationThread.aidl

@@ -154,4 +154,5 @@ oneway interface IApplicationThread {
     void handleTrustStorageUpdate();
     void attachAgent(String path);
     void scheduleApplicationInfoChanged(in ApplicationInfo ai);
+    void setNetworkBlockSeq(long procStateSeq);
 }