Persist Instance ID data to GCM store.

components/gcm_driver/fake_gcm_client.h

Index: components/gcm_driver/fake_gcm_client.h
diff --git a/components/gcm_driver/fake_gcm_client.h b/components/gcm_driver/fake_gcm_client.h
index 21d696d70edbd89836999d7a6e68b4d97afa2ef6..c0b03daba88b17fbc856e8cb3c815001808468f5 100644
--- a/components/gcm_driver/fake_gcm_client.h
+++ b/components/gcm_driver/fake_gcm_client.h
@@ -56,6 +56,10 @@ class FakeGCMClient : public GCMClient {
   void RemoveAccountMapping(const std::string& account_id) override;
   void SetLastTokenFetchTime(const base::Time& time) override;
   void UpdateHeartbeatTimer(scoped_ptr<base::Timer> timer) override;
+  void AddInstanceIDData(const std::string& app_id,
+                         const std::string& instance_id_data) override;
+  void RemoveInstanceIDData(const std::string& app_id) override;
+  std::string GetInstanceIDData(const std::string& app_id) override;
 
   // Initiate the start that has been delayed.
   // Called on UI thread.