Move Screen, its impls, DisplayObserver and DisplayChangeNotifier to ui/display

ui/display/test/test_screen.h

 // Copyright 2015 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 UI_DISPLAY_TEST_TEST_SCREEN_H_
 #define UI_DISPLAY_TEST_TEST_SCREEN_H_
 
 #include <vector>
 
 #include "base/macros.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 
 namespace display {
 namespace test {
 
 // A dummy implementation of display::Screen that contains a single
 // display::Display only. The contained Display can be accessed and modified via
 // TestScreen::display().
 //
 // NOTE: Adding and removing display::DisplayOberver's are no-ops and observers
 // will NOT be notified ever.
 class TestScreen : public Screen {
  public:
   TestScreen();
   ~TestScreen() override;
 
   Display* display() { return &display_; }
 
-  // Screen:
+  // display::Screen:
   gfx::Point GetCursorScreenPoint() override;
   bool IsWindowUnderCursor(gfx::NativeWindow window) override;
   gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override;
   int GetNumDisplays() const override;
   std::vector<Display> GetAllDisplays() const override;
   Display GetDisplayNearestWindow(gfx::NativeView view) const override;
   Display GetDisplayNearestPoint(const gfx::Point& point) const override;
   Display GetDisplayMatching(const gfx::Rect& match_rect) const override;
   Display GetPrimaryDisplay() const override;
   void AddObserver(DisplayObserver* observer) override;
   void RemoveObserver(DisplayObserver* observer) override;
 
  private:
   // The only display.
   Display display_;
 
   DISALLOW_COPY_AND_ASSIGN(TestScreen);
 };
 
 }  // namespace test
 }  // namespace display
 
 #endif  // UI_DISPLAY_TEST_TEST_SCREEN_H_