Move DisplayChangeObserver + tests from ash to ui.

ui/display/chromeos/display_change_observer.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_DISPLAY_CHANGE_OBSERVER_CHROMEOS_H_
-#define ASH_DISPLAY_DISPLAY_CHANGE_OBSERVER_CHROMEOS_H_
+#ifndef UI_DISPLAY_CHROMEOS_DISPLAY_CHANGE_OBSERVER_H_
+#define UI_DISPLAY_CHROMEOS_DISPLAY_CHANGE_OBSERVER_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <vector>
 
-#include "ash/ash_export.h"
+#include "base/callback.h"
 #include "base/macros.h"
 #include "ui/display/chromeos/display_configurator.h"
+#include "ui/display/display_export.h"
 #include "ui/display/manager/display_string_provider.h"
 #include "ui/display/manager/managed_display_info.h"
 #include "ui/events/devices/input_device_event_observer.h"
 
 namespace display {
+
 class DisplayManager;
-}
-
-namespace ash {
-
 class DisplaySnapshot;
 
 // An object that observes changes in display configuration and updates
 // DisplayManager.
-class DisplayChangeObserver : public ui::DisplayConfigurator::StateController,
-                              public ui::DisplayConfigurator::Observer,
-                              public ui::InputDeviceEventObserver {
+class DISPLAY_EXPORT DisplayChangeObserver

[sadrul, 2016/11/29 02:09:27]

Hm. display::DisplayChangeObserver gets updates from
display::DisplayConfigurator, and notifies display::DisplayManager. Why does the
external code need to set it up explicitly? Can this be set up by either the
DisplayConfigurator and/or DisplayManager instead?

[kylechar, 2016/11/29 14:37:07]

I think it kind of just evolved this way. I tried to keep the structure as
similar as possible in this CL. Having DisplayConfigurator create
DisplayChangeObserver would work fine, except for //ui/display can't add the
UserActivityDetector callback (but the callback could be added to
DisplayConfigurator instead from ash or there could be a new
//ui/display/chromeos target added).

In general there is a lot of refactoring that could go into the
DisplayConfigurator --> DisplayChangeObserver --> DisplayManager system but I'm
not convinced it should happen in the same CL that moves DisplayChangeObserver.

[sadrul, 2016/11/29 18:24:40]

Oh yeah, that shouldn't happen with the file-move. Maybe file a bug and
reference that from here so this is tracked? If there are other cleanups that
are possible, it'd be good to file separate bugs for those too.

+    : public ui::DisplayConfigurator::StateController,
+      public ui::DisplayConfigurator::Observer,
+      public ui::InputDeviceEventObserver {
  public:
   // Returns the mode list for internal display.
-  ASH_EXPORT static display::ManagedDisplayInfo::ManagedDisplayModeList
-  GetInternalManagedDisplayModeList(
-      const display::ManagedDisplayInfo& display_info,
-      const ui::DisplaySnapshot& output);
+  DISPLAY_EXPORT static ManagedDisplayInfo::ManagedDisplayModeList
+  GetInternalManagedDisplayModeList(const ManagedDisplayInfo& display_info,
+                                    const ui::DisplaySnapshot& output);
 
   // Returns the resolution list.
-  ASH_EXPORT static display::ManagedDisplayInfo::ManagedDisplayModeList
+  DISPLAY_EXPORT static ManagedDisplayInfo::ManagedDisplayModeList
   GetExternalManagedDisplayModeList(const ui::DisplaySnapshot& output);
 
   explicit DisplayChangeObserver(
-      std::unique_ptr<display::DisplayStringProvider> string_provider);
+      std::unique_ptr<DisplayStringProvider> string_provider);
   ~DisplayChangeObserver() override;
 
-  void set_display_manager(display::DisplayManager* display_manager) {
+  void set_display_manager(DisplayManager* display_manager) {
     display_manager_ = display_manager;
   }
 
   void set_display_configurator(ui::DisplayConfigurator* display_configurator) {
     display_configurator_ = display_configurator;
   }
 
+  // Sets callback to be called when the display state is potentially changing.
+  void set_display_changing_callback(base::Closure display_changing_callback) {
+    display_changing_callback_ = display_changing_callback;
+  }
+
   // ui::DisplayConfigurator::StateController overrides:
   ui::MultipleDisplayState GetStateForDisplayIds(
       const ui::DisplayConfigurator::DisplayStateList& outputs) const override;
   bool GetResolutionForDisplayId(int64_t display_id,
                                  gfx::Size* size) const override;
 
   // Overriden from ui::DisplayConfigurator::Observer:
   void OnDisplayModeChanged(
       const ui::DisplayConfigurator::DisplayStateList& outputs) override;
   void OnDisplayModeChangeFailed(
       const ui::DisplayConfigurator::DisplayStateList& displays,
       ui::MultipleDisplayState failed_new_state) override;
 
   // Overriden from ui::InputDeviceEventObserver:
   void OnTouchscreenDeviceConfigurationChanged() override;
 
   // Exposed for testing.
-  ASH_EXPORT static float FindDeviceScaleFactor(float dpi);
+  DISPLAY_EXPORT static float FindDeviceScaleFactor(float dpi);
 
  private:
-  std::unique_ptr<display::DisplayStringProvider> string_provider_;
-  display::DisplayManager* display_manager_ = nullptr;
+  std::unique_ptr<DisplayStringProvider> string_provider_;
+  DisplayManager* display_manager_ = nullptr;
   ui::DisplayConfigurator* display_configurator_ = nullptr;
 
+  // Called when display state is about to change.
+  base::Closure display_changing_callback_;
+
   DISALLOW_COPY_AND_ASSIGN(DisplayChangeObserver);
 };
 
-}  // namespace ash
+}  // namespace display
 
-#endif  // ASH_DISPLAY_DISPLAY_CHANGE_OBSERVER_CHROMEOS_H_
+#endif  // UI_DISPLAY_CHROMEOS_DISPLAY_CHANGE_OBSERVER_H_