[GCM] Exposing persistence of account mappings in GCM Driver

components/gcm_driver/fake_gcm_client.cc

Index: components/gcm_driver/fake_gcm_client.cc
diff --git a/components/gcm_driver/fake_gcm_client.cc b/components/gcm_driver/fake_gcm_client.cc
index 6a5639c6ae7689a35507e29d042de1b232000363..9110d1b1d6088bf9018b9fb44b9ba1403d0733fe 100644
--- a/components/gcm_driver/fake_gcm_client.cc
+++ b/components/gcm_driver/fake_gcm_client.cc
@@ -119,6 +119,13 @@ void FakeGCMClient::SetAccountsForCheckin(
     const std::map<std::string, std::string>& account_tokens) {
 }
 
+void FakeGCMClient::UpdateAccountMapping(
+    const AccountMapping& account_mapping) {
+}
+
+void FakeGCMClient::RemoveAccountMapping(const std::string& account_id) {
+}
+
 void FakeGCMClient::PerformDelayedLoading() {
   DCHECK(ui_thread_->RunsTasksOnCurrentThread());