Add display::GetDisplayNearestView

content/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 2012 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.
 
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <Carbon/Carbon.h>
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
@@ skipping 673 matching lines @@
   pepper_fullscreen_window_.reset();
 }
 
 int RenderWidgetHostViewMac::window_number() const {
   NSWindow* window = [cocoa_view_ window];
   if (!window)
     return -1;
   return [window windowNumber];
 }
 
 float RenderWidgetHostViewMac::ViewScaleFactor() const {

[tapted, 2017/02/15 00:36:10]

This method should just be deleted. Callers should either use
current_device_scale_factor() from the parent class, or the
GetScaleFactorForNativeView() method that you're adding.

[Jinsuk Kim, 2017/02/16 10:11:25]

Done.

-  return ui::GetScaleFactorForNativeView(cocoa_view_);
+  return GetScaleFactorForNativeView(cocoa_view_);
 }
 
 void RenderWidgetHostViewMac::UpdateDisplayLink() {
   static bool is_vsync_disabled =
       base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableGpuVsync);
   if (is_vsync_disabled)
     return;
 
   NSScreen* screen = [[cocoa_view_ window] screen];
@@ skipping 2767 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end