Change to pass by const reference for a couple GCMDriverDesktop methods

BUG=none

Review URL: https://codereview.chromium.org/301243019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274453 0039d316-1c4b-4281-b951-d872f2087c98

components/gcm_driver/gcm_driver_desktop.cc

@@ -746,8 +746,9 @@ void GCMDriverDesktop::SendFinished(const std::string& app_id,
   callback.Run(message_id, result);
 }
 
-void GCMDriverDesktop::MessageReceived(const std::string& app_id,
-                                       GCMClient::IncomingMessage message) {
+void GCMDriverDesktop::MessageReceived(
+    const std::string& app_id,
+    const GCMClient::IncomingMessage& message) {
   DCHECK(ui_thread_->RunsTasksOnCurrentThread());
 
   // Drop the event if signed out.
@@ -790,7 +791,7 @@ void GCMDriverDesktop::GCMClientReady() {
 }
 
 void GCMDriverDesktop::GetGCMStatisticsFinished(
-    GCMClient::GCMStatistics stats) {
+    const GCMClient::GCMStatistics& stats) {
   DCHECK(ui_thread_->RunsTasksOnCurrentThread());
 
   // Normally request_gcm_statistics_callback_ would not be null.

components/gcm_driver/gcm_driver_desktop.h

@@ -120,13 +120,13 @@ class GCMDriverDesktop : public GCMDriver, public IdentityProvider::Observer {
                     const std::string& message_id,
                     GCMClient::Result result);
   void MessageReceived(const std::string& app_id,
-                       GCMClient::IncomingMessage message);
+                       const GCMClient::IncomingMessage& message);
   void MessagesDeleted(const std::string& app_id);
   void MessageSendError(const std::string& app_id,
                         const GCMClient::SendErrorDetails& send_error_details);
   void GCMClientReady();
 
-  void GetGCMStatisticsFinished(GCMClient::GCMStatistics stats);
+  void GetGCMStatisticsFinished(const GCMClient::GCMStatistics& stats);
 
   // Flag to indicate if GCM is enabled.
   bool gcm_enabled_;