Make SetDisplayPower() take a callback to signal completion

chromeos/dbus/services/display_power_service_provider.h

 // Copyright (c) 2013 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.
 
 #ifndef CHROMEOS_DBUS_SERVICES_DISPLAY_POWER_SERVICE_PROVIDER_H_
 #define CHROMEOS_DBUS_SERVICES_DISPLAY_POWER_SERVICE_PROVIDER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 13 matching lines @@
 namespace chromeos {
 
 // This class exports "SetDisplayPower" and "SetDisplaySoftwareDimming"
 // D-Bus methods that the power manager calls to instruct Chrome to turn
 // various displays on or off or dim them.
 class CHROMEOS_EXPORT DisplayPowerServiceProvider
     : public CrosDBusService::ServiceProviderInterface {
  public:
   class Delegate {
    public:
+    typedef base::Callback<void(bool)> ResponseCallback;
+
     virtual ~Delegate() {}
 
-    // Sets the display power state.
-    virtual void SetDisplayPower(DisplayPowerState power_state) = 0;
+    // Sets the display power state. After the display power is set, |callback|
+    // is called with the operation status.
+    virtual void SetDisplayPower(DisplayPowerState power_state,
+                                 const ResponseCallback& callback) = 0;
 
     // Dims or undims the screen.
     virtual void SetDimming(bool dimmed) = 0;
   };
 
   explicit DisplayPowerServiceProvider(scoped_ptr<Delegate> delegate);
   ~DisplayPowerServiceProvider() override;
 
   // CrosDBusService::ServiceProviderInterface overrides:
   void Start(scoped_refptr<dbus::ExportedObject> exported_object) override;
@@ skipping 17 matching lines @@
   // Keep this last so that all weak pointers will be invalidated at the
   // beginning of destruction.
   base::WeakPtrFactory<DisplayPowerServiceProvider> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayPowerServiceProvider);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_SERVICES_DISPLAY_POWER_SERVICE_PROVIDER_H_