Introduce user customization of external HighDPI mode for 4K monitor.

ash/display/resolution_notification_controller.h

 // Copyright 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 ASH_DISPLAY_RESOLUTION_NOTIFICATION_CONTROLLER_H_
 #define ASH_DISPLAY_RESOLUTION_NOTIFICATION_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "ash/display/display_controller.h"
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/timer/timer.h"
 #include "ui/gfx/display_observer.h"
 #include "ui/gfx/size.h"
 
 namespace chromeos {
 FORWARD_DECLARE_TEST(DisplayPreferencesTest, PreventStore);
 }  // namespace chromeos
 
 namespace views {
 class Label;
 class Widget;
 }  // namespace views
 
 namespace ash {
 
+struct DisplayMode;
+
 // A class which manages the notification of display resolution change and
 // also manages the timeout in case the new resolution is unusable.
 class ASH_EXPORT ResolutionNotificationController
     : public gfx::DisplayObserver,
       public DisplayController::Observer {
  public:
   ResolutionNotificationController();
   virtual ~ResolutionNotificationController();
 
-  // Updates the display resolution for |display_id| to |new_resolution| and
-  // creates a notification for this change which offers a button to revert the
+  // Prepare a resolution change notification for |display_id| from
+  // |old_resolution| to |new_resolution|, which offers a button to revert the
   // change in case something goes wrong. The notification times out if there's
   // only one display connected and the user is trying to modify its resolution.
   // In that case, the timeout has to be set since the user cannot make any
   // changes if something goes wrong.
-  void SetDisplayResolutionAndNotify(
-      int64 display_id,
-      const gfx::Size& old_resolution,
-      const gfx::Size& new_resolution,
-      const base::Closure& accept_callback);
+  //
+  // This method does not create a notification itself. The notification will be
+  // created the next OnDisplayConfigurationChanged(), which will be called
+  // asynchronously after the resolution change is requested. So typically this
+  // method will be combined with resolution change methods like
+  // DisplayManager::SetDisplayMode().
+  void PrepareNotification(int64 display_id,
+                           const DisplayMode& old_resolution,
+                           const DisplayMode& new_resolution,
+                           const base::Closure& accept_callback);
 
   // Returns true if the notification is visible or scheduled to be visible and
   // the notification times out.
   bool DoesNotificationTimeout();
 
   // Called by the notification delegate when the user accepts the display
   // resolution change. Set |close_notification| to true when the notification
   // should be removed.
   void AcceptResolutionChange(bool close_notification);
 
@@ skipping 33 matching lines @@
   static void SuppressTimerForTest();
 
   scoped_ptr<ResolutionChangeInfo> change_info_;
 
   DISALLOW_COPY_AND_ASSIGN(ResolutionNotificationController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_RESOLUTION_NOTIFICATION_CONTROLLER_H_