[Background Sync] Use GcmNetworkManager to start the browser for sync events.

content/public/android/java/src/org/chromium/content/browser/BackgroundSyncLauncher.java

Index: content/public/android/java/src/org/chromium/content/browser/BackgroundSyncLauncher.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/BackgroundSyncLauncher.java b/content/public/android/java/src/org/chromium/content/browser/BackgroundSyncLauncher.java
index bad267185182d208dcaf14efc6b12dae6704278a..510a5b461a899cfeaff545ec63b27982e6520df2 100644
--- a/content/public/android/java/src/org/chromium/content/browser/BackgroundSyncLauncher.java
+++ b/content/public/android/java/src/org/chromium/content/browser/BackgroundSyncLauncher.java
@@ -9,6 +9,10 @@ import android.content.SharedPreferences;
 import android.os.AsyncTask;
 import android.preference.PreferenceManager;
 
+import com.google.android.gms.gcm.GcmNetworkManager;
+import com.google.android.gms.gcm.OneoffTask;
+import com.google.android.gms.gcm.Task;
+
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
@@ -28,6 +32,8 @@ public class BackgroundSyncLauncher {
     // BackgroundSyncLauncherAndroid, if any. If it is non-null then the browser is running.
     private static BackgroundSyncLauncher sInstance;
 
+    private GcmNetworkManager mScheduler;
+
     /**
      * Create a BackgroundSyncLauncher object, which is owned by C++.
      * @param context The app context.
@@ -58,6 +64,26 @@ public class BackgroundSyncLauncher {
      */
     public static interface ShouldLaunchCallback { public void run(Boolean shouldLaunch); }
 
+    private void scheduleLaunchTask() {

[jkarlin, 2015/09/02 18:16:36]

It appears that this can be called multiple times, resulting in multiple tasks.
Should we check for this? Or perhaps removeScheduledTasks() first?

[iclelland, 2015/09/02 20:04:48]

If it is called when there is already a task scheduled, the re-use of the same
tag ("BackgroundSync Event") means that the existing task will just be updated.

[jkarlin, 2015/09/03 11:11:57]

Acknowledged.

+        // Google Play Services may not be up to date, if the application was not installed through
+        // the Play Store. In this case, scheduling the task will fail silently.
+        // TODO(iclelland): Check whether the Play Services client library matches the requirements
+        // in the manifest, and respond appropriately if it does not.
+        OneoffTask oneoff = new OneoffTask.Builder()
+                .setService(BackgroundSyncLauncherService.class)
+                .setTag("BackgroundSync Event")
+                .setExecutionWindow(0, 0)
+                .setRequiredNetwork(Task.NETWORK_STATE_CONNECTED)
+                .setPersisted(true)
+                .setUpdateCurrent(true)
+                .build();
+        mScheduler.schedule(oneoff);
+    }
+
+    private void removeScheduledTasks() {
+        mScheduler.cancelAllTasks(BackgroundSyncLauncherService.class);
+    }
+
     /**
      * Returns whether the browser should be launched when the device next goes online.
      * This is set by C++ and reset to false each time {@link BackgroundSyncLauncher}'s singleton is
@@ -101,6 +127,11 @@ public class BackgroundSyncLauncher {
                 return null;
             }
         }.execute();
+        if (shouldLaunch) {
+            scheduleLaunchTask();
+        } else {
+            removeScheduledTasks();
+        }
     }
 
     /**
@@ -112,6 +143,7 @@ public class BackgroundSyncLauncher {
     }
 
     private BackgroundSyncLauncher(Context context) {
+        mScheduler = GcmNetworkManager.getInstance(context);
         setLaunchWhenNextOnline(context, false);
     }
-}
+}