Set device scale factor in CompositorFrame and scale frame size in WS.

ui/display/screen_base.cc

 // Copyright 2016 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.
 
 // This has to be before any other includes, else default is picked up.
 // See base/logging for details on this.
 #define NOTIMPLEMENTED_POLICY 5
 
 #include "ui/display/screen_base.h"
 
@@ skipping 21 matching lines @@
 }
 
 Display ScreenBase::GetPrimaryDisplay() const {
   auto iter = display_list_.GetPrimaryDisplayIterator();
   if (iter == display_list_.displays().end())
     return Display();  // Invalid display since we have no primary display.
   return *iter;
 }
 
 Display ScreenBase::GetDisplayNearestWindow(gfx::NativeView view) const {
+  // TODO(riajiang): Implement this for multi-displays either here or in

[sky, 2016/12/16 18:11:49]

ScreenMus may end up using ScreenAsh. But we'll straighten that out later.

+  // ScreenMus.
   NOTIMPLEMENTED();
   return GetPrimaryDisplay();
 }
 
 Display ScreenBase::GetDisplayNearestPoint(const gfx::Point& point) const {
   return *FindDisplayNearestPoint(display_list_.displays(), point);
 }
 
 int ScreenBase::GetNumDisplays() const {
   return static_cast<int>(display_list_.displays().size());
@@ skipping 25 matching lines @@
                              is_primary ? DisplayList::Type::PRIMARY
                                         : DisplayList::Type::NOT_PRIMARY);
     return;
   }
   display_list_.UpdateDisplay(
       changed_display,
       is_primary ? DisplayList::Type::PRIMARY : DisplayList::Type::NOT_PRIMARY);
 }
 
 }  // namespace display