chromeos: Convert D-Bus client classes' callback arguments to const reference

chromeos/dbus/update_engine_client.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chromeos/dbus/update_engine_client.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/string_util.h"
 #include "dbus/bus.h"
@@ skipping 69 matching lines @@
   virtual void RemoveObserver(Observer* observer) OVERRIDE {
     observers_.RemoveObserver(observer);
   }
 
   // UpdateEngineClient override.
   virtual bool HasObserver(Observer* observer) OVERRIDE {
     return observers_.HasObserver(observer);
   }
 
   // UpdateEngineClient override.
-  virtual void RequestUpdateCheck(UpdateCheckCallback callback) OVERRIDE {
+  virtual void RequestUpdateCheck(
+      const UpdateCheckCallback& callback) OVERRIDE {
     dbus::MethodCall method_call(
         update_engine::kUpdateEngineInterface,
         update_engine::kAttemptUpdate);
     dbus::MessageWriter writer(&method_call);
     writer.AppendString("");  // Unused.
     writer.AppendString("");  // Unused.
 
     VLOG(1) << "Requesting an update check";
     update_engine_proxy_->CallMethod(
         &method_call,
@@ skipping 27 matching lines @@
 
     VLOG(1) << "Requesting to set the release track to " << track;
     update_engine_proxy_->CallMethod(
         &method_call,
         dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
         base::Bind(&UpdateEngineClientImpl::OnSetReleaseTrack,
                    weak_ptr_factory_.GetWeakPtr()));
   }
 
   // UpdateEngineClient override.
-  virtual void GetReleaseTrack(GetReleaseTrackCallback callback) OVERRIDE {
+  virtual void GetReleaseTrack(
+      const GetReleaseTrackCallback& callback) OVERRIDE {
     dbus::MethodCall method_call(
         update_engine::kUpdateEngineInterface,
         update_engine::kGetTrack);
 
     VLOG(1) << "Requesting to get the current release track";
     update_engine_proxy_->CallMethod(
         &method_call,
         dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
         base::Bind(&UpdateEngineClientImpl::OnGetReleaseTrack,
                    weak_ptr_factory_.GetWeakPtr(),
                    callback));
   }
 
   // UpdateEngineClient override.
   virtual Status GetLastStatus() OVERRIDE {
     return last_status_;
   }
 
  private:
   // Called when a response for RequestUpdateCheck() is received.
-  void OnRequestUpdateCheck(UpdateCheckCallback callback,
+  void OnRequestUpdateCheck(const UpdateCheckCallback& callback,
                             dbus::Response* response) {
     if (!response) {
       LOG(ERROR) << "Failed to request update check";
       callback.Run(UPDATE_RESULT_FAILED);
       return;
     }
     callback.Run(UPDATE_RESULT_SUCCESS);
   }
 
   // Called when a response for RebootAfterUpdate() is received.
   void OnRebootAfterUpdate(dbus::Response* response) {
     if (!response) {
       LOG(ERROR) << "Failed to request rebooting after update";
       return;
     }
   }
 
   // Called when a response for SetReleaseTrack() is received.
   void OnSetReleaseTrack(dbus::Response* response) {
     if (!response) {
       LOG(ERROR) << "Failed to request setting release track";
       return;
     }
   }
 
   // Called when a response for GetReleaseTrack() is received.
-  void OnGetReleaseTrack(GetReleaseTrackCallback callback,
+  void OnGetReleaseTrack(const GetReleaseTrackCallback& callback,
                          dbus::Response* response) {
     if (!response) {
       LOG(ERROR) << "Failed to request getting release track";
       callback.Run("");
       return;
     }
     dbus::MessageReader reader(response);
     std::string release_track;
     if (!reader.PopString(&release_track)) {
       LOG(ERROR) << "Incorrect response: " << response->ToString();
@@ skipping 50 matching lines @@
 };
 
 // The UpdateEngineClient implementation used on Linux desktop,
 // which does nothing.
 class UpdateEngineClientStubImpl : public UpdateEngineClient {
   // UpdateEngineClient overrides.
   virtual void AddObserver(Observer* observer) OVERRIDE {}
   virtual void RemoveObserver(Observer* observer) OVERRIDE {}
   virtual bool HasObserver(Observer* observer) OVERRIDE { return false; }
 
-  virtual void RequestUpdateCheck(UpdateCheckCallback callback) OVERRIDE {
+  virtual void RequestUpdateCheck(
+      const UpdateCheckCallback& callback) OVERRIDE {
     callback.Run(UPDATE_RESULT_NOTIMPLEMENTED);
   }
   virtual void RebootAfterUpdate() OVERRIDE {}
   virtual void SetReleaseTrack(const std::string& track) OVERRIDE {}
-  virtual void GetReleaseTrack(GetReleaseTrackCallback callback) OVERRIDE {
+  virtual void GetReleaseTrack(
+      const GetReleaseTrackCallback& callback) OVERRIDE {
     callback.Run("beta-channel");
   }
   virtual Status GetLastStatus() OVERRIDE { return Status(); }
 };
 
 UpdateEngineClient::UpdateEngineClient() {
 }
 
 UpdateEngineClient::~UpdateEngineClient() {
 }
 
 // static
 UpdateEngineClient::UpdateCheckCallback
 UpdateEngineClient::EmptyUpdateCheckCallback() {
   return base::Bind(&EmptyUpdateCheckCallbackBody);
 }
 
 // static
 UpdateEngineClient* UpdateEngineClient::Create(
     DBusClientImplementationType type,
     dbus::Bus* bus) {
   if (type == REAL_DBUS_CLIENT_IMPLEMENTATION)
     return new UpdateEngineClientImpl(bus);
   DCHECK_EQ(STUB_DBUS_CLIENT_IMPLEMENTATION, type);
   return new UpdateEngineClientStubImpl();
 }
 
 }  // namespace chromeos