Implement GCMDriver.java using MultiplexingGcmListener

sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java

Index: sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java
diff --git a/sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java b/sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java
index 03805ecaa5859d95e9a3253e482b387683797a18..a1f6f851cb1d8081c7bc17db85f2d97fe5095286 100644
--- a/sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java
+++ b/sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java
@@ -13,7 +13,9 @@ import android.util.Log;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.ipc.invalidation.external.client.contrib.MultiplexingGcmListener;
 
+import org.chromium.base.CommandLine;
 import org.chromium.base.ObserverList;
+import org.chromium.sync.SyncSwitches;
 
 public class ChromeSigninController {
     public interface Listener {
@@ -114,6 +116,11 @@ public class ChromeSigninController {
         new AsyncTask<Void, Void, Void>() {
             @Override
             protected Void doInBackground(Void... arg0) {
+                if (CommandLine.getInstance().hasSwitch(
+                        SyncSwitches.DISABLE_SYNC_GCM_IN_ORDER_TO_TRY_PUSH_API)) {
+                    Log.w(TAG, "Sync GCM notifications disabled in order to try Push API!");
+                    return null;
+                }
                 try {
                     String regId = MultiplexingGcmListener.initializeGcm(mApplicationContext);
                     if (!regId.isEmpty())