[GCM] Exposing persistence of account mappings in GCM Driver

components/gcm_driver/fake_gcm_driver.cc

Index: components/gcm_driver/fake_gcm_driver.cc
diff --git a/components/gcm_driver/fake_gcm_driver.cc b/components/gcm_driver/fake_gcm_driver.cc
index 0b98775953ce972e75ca1f2adeed4cbc6c10d4f8..573140e709976a4ab81e3217b9fc5cbf970f9165 100644
--- a/components/gcm_driver/fake_gcm_driver.cc
+++ b/components/gcm_driver/fake_gcm_driver.cc
@@ -70,4 +70,11 @@ void FakeGCMDriver::SendImpl(const std::string& app_id,
                              const GCMClient::OutgoingMessage& message) {
 }
 
+void FakeGCMDriver::UpdateAccountMapping(
+    const AccountMapping& account_mapping) {
+}
+
+void FakeGCMDriver::RemoveAccountMapping(const std::string& account_id) {
+}
+
 }  // namespace gcm