Adds GetDisplays() to WindowManager

ui/mojo/init/screen_mojo.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_MOJO_INIT_SCREEN_MOJO_H_
 #define UI_MOJO_INIT_SCREEN_MOJO_H_
 
+#include <vector>
+
 #include "ui/gfx/display.h"
-#include "ui/gfx/geometry/size.h"
 #include "ui/gfx/screen.h"
 
 namespace ui {
 namespace mojo {
 
 class ScreenMojo : public gfx::Screen {
  public:
-  ScreenMojo(const gfx::Size& screen_size_in_pixels, float device_pixel_ratio);
+  explicit ScreenMojo(const std::vector<gfx::Display>& displays);
+  ~ScreenMojo() override;
 
   // gfx::Screen:
   gfx::Point GetCursorScreenPoint() override;
   gfx::NativeWindow GetWindowUnderCursor() override;
   gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override;
   gfx::Display GetPrimaryDisplay() const override;
   gfx::Display GetDisplayNearestWindow(gfx::NativeView view) const override;
   gfx::Display GetDisplayNearestPoint(const gfx::Point& point) const override;
   int GetNumDisplays() const override;
   std::vector<gfx::Display> GetAllDisplays() const override;
   gfx::Display GetDisplayMatching(const gfx::Rect& match_rect) const override;
   void AddObserver(gfx::DisplayObserver* observer) override;
   void RemoveObserver(gfx::DisplayObserver* observer) override;
 
  private:
-  const gfx::Size screen_size_in_pixels_;
-  const float device_pixel_ratio_;
-
-  gfx::Display display_;
+  const std::vector<gfx::Display> displays_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenMojo);
 };
 
 }  // namespace mojo
 }  // namespace ui
 
 #endif  // UI_MOJO_INIT_SCREEN_MOJO_H_