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

chrome/android/java/src/org/chromium/chrome/browser/BackgroundSyncLauncherService.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser;
+
+import android.content.Context;
+
+import com.google.android.gms.gcm.GcmNetworkManager;
+import com.google.android.gms.gcm.GcmTaskService;
+import com.google.android.gms.gcm.TaskParams;
+
+import org.chromium.base.Log;
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.SuppressFBWarnings;
+import org.chromium.base.library_loader.LibraryProcessType;
+import org.chromium.base.library_loader.ProcessInitException;
+import org.chromium.content.app.ContentApplication;
+import org.chromium.content.browser.BrowserStartupController;
+
+/**
+ * {@link BackgroundSyncLauncherService} is scheduled through the {@link GcmNetworkManager}
+ * when the browser needs to be launched in response to changing network or power conditions.
+ */
+public class BackgroundSyncLauncherService extends GcmTaskService {
+    private static final String TAG = "cr_BgSyncLauncher";
+
+    @Override
+    @VisibleForTesting
+    public int onRunTask(TaskParams params) {
+        // Start the browser. The browser's BackgroundSyncManager (for the active profile) will
+        // start, check the network, and run any necessary sync events. This task runs with a wake
+        // lock, but has a three minute timeout, so we need to start the browser in its own task.
+        // TODO(jkarlin): Protect the browser sync event with a wake lock. See crbug.com/486020.
+        Log.v(TAG, "Starting Browser after coming online");
+        final Context context = this;
+        ThreadUtils.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                if (!BackgroundSyncLauncher.hasInstance()) {
+                    launchBrowser(context);
+                }
+            }
+        });
+        return GcmNetworkManager.RESULT_SUCCESS;
+    }
+
+    @VisibleForTesting
+    @SuppressFBWarnings("DM_EXIT")
+    protected void launchBrowser(Context context) {
+        ContentApplication.initCommandLine(context);
+        try {
+            BrowserStartupController.get(context, LibraryProcessType.PROCESS_BROWSER)
+                    .startBrowserProcessesSync(false);
+        } catch (ProcessInitException e) {
+            Log.e(TAG, "ProcessInitException while starting the browser process");
+            // Since the library failed to initialize nothing in the application
+            // can work, so kill the whole application not just the activity.
+            System.exit(-1);
+        }
+    }
+
+    @Override
+    @VisibleForTesting
+    public void onInitializeTasks() {
+        BackgroundSyncLauncher.rescheduleTasksOnUpgrade(this);
+    }
+}