Keep the GCM data intact when the user signs out of the profile

components/gcm_driver/gcm_driver_desktop.h

Index: components/gcm_driver/gcm_driver_desktop.h
diff --git a/components/gcm_driver/gcm_driver_desktop.h b/components/gcm_driver/gcm_driver_desktop.h
index 5a44f58e286d30c8720e079e5affa14e9a93a816..a73d38ca30d3e05b0aa6f09c9b6c509a325f7c52 100644
--- a/components/gcm_driver/gcm_driver_desktop.h
+++ b/components/gcm_driver/gcm_driver_desktop.h
@@ -59,6 +59,7 @@ class GCMDriverDesktop : public GCMDriver {
   // GCMDriver overrides:
   virtual void Shutdown() OVERRIDE;
   virtual void OnSignedIn() OVERRIDE;
+  virtual void OnSignedOut() OVERRIDE;
   virtual void Purge() OVERRIDE;
   virtual void AddAppHandler(const std::string& app_id,
                              GCMAppHandler* handler) OVERRIDE;