[GCM] Stop/restart GCM when the state is forced off/on

google_apis/gcm/gcm_client.h

Index: google_apis/gcm/gcm_client.h
diff --git a/google_apis/gcm/gcm_client.h b/google_apis/gcm/gcm_client.h
index 15f67cf21665f061bc03a903440ae68ac5666c12..a25cb12e933c8f9fc15b6f56e7727e47f2d72528 100644
--- a/google_apis/gcm/gcm_client.h
+++ b/google_apis/gcm/gcm_client.h
@@ -153,8 +153,12 @@ class GCM_EXPORT GCMClient {
 
   // Loads the data from the persistent store. This will automatically kick off
   // the check-in if the check-in info is not found in the store.
+  // TODO(jianli): consider renaming this name to Start.
   virtual void Load() = 0;
 
+  // Stops using the GCM service. This will not erase the persisted data.
+  virtual void Stop() = 0;
+
   // Checks out of the GCM service. This will erase all the cached and persisted
   // data.
   virtual void CheckOut() = 0;