Notify GCMAppHandlers when the store is reset, so they clear cached IDs

components/gcm_driver/gcm_client.h

Index: components/gcm_driver/gcm_client.h
diff --git a/components/gcm_driver/gcm_client.h b/components/gcm_driver/gcm_client.h
index b3f65431debdef1ebbcd4cb62e6d43840ec02df2..30be5ffbd6f8984246b3c23ebd820206660ebe6e 100644
--- a/components/gcm_driver/gcm_client.h
+++ b/components/gcm_driver/gcm_client.h
@@ -214,6 +214,10 @@ class GCMClient {
 
     // Called when the connection is interrupted.
     virtual void OnDisconnected() = 0;
+
+    // Called when the GCM store is reset (e.g. due to corruption), which
+    // changes the device ID, invalidating all prior registrations.
+    virtual void OnStoreReset() = 0;
   };
 
   GCMClient();