Use physical pixels for display root ServerWindow.

services/ui/ws/display.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 SERVICES_UI_WS_DISPLAY_H_
 #define SERVICES_UI_WS_DISPLAY_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 145 matching lines @@
   // Inits the necessary state once the display is ready.
   void InitWindowManagerDisplayRootsIfNecessary();
 
   // Creates the set of WindowManagerDisplayRoots from the
   // WindowManagerWindowTreeFactorySet.
   void CreateWindowManagerDisplayRootsFromFactories();
 
   void CreateWindowManagerDisplayRootFromFactory(
       WindowManagerWindowTreeFactory* factory);
 
-  // Creates the root ServerWindow for this display. The root window will have
-  // |size| in DIP.
+  // Creates the root ServerWindow for this display, where |size| is in physical
+  // pixels.
   void CreateRootWindow(const gfx::Size& size);
 
   // PlatformDisplayDelegate:
   ServerWindow* GetRootWindow() override;
   bool IsInHighContrastMode() override;
   void OnEvent(const ui::Event& event) override;
   void OnNativeCaptureLost() override;
 
   // FocusControllerDelegate:
   bool CanHaveActiveChildren(ServerWindow* window) const override;
@@ skipping 27 matching lines @@
 
   WindowManagerDisplayRootMap window_manager_display_root_map_;
 
   DISALLOW_COPY_AND_ASSIGN(Display);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_DISPLAY_H_