Support error handling for Surface readbacks

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 <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
 
@@ skipping 1165 matching lines @@
   ForwardMouseEvent(web_event);
 }
 
 bool RenderWidgetHostViewMac::IsPopup() const {
   return popup_type_ != blink::WebPopupTypeNone;
 }
 
 void RenderWidgetHostViewMac::CopyFromCompositingSurface(
     const gfx::Rect& src_subrect,
     const gfx::Size& dst_size,
-    const base::Callback<void(bool, const SkBitmap&)>& callback,
+    ReadbackRequestCallback& callback,
     const SkColorType color_type) {
   if (delegated_frame_host_) {
     delegated_frame_host_->CopyFromCompositingSurface(
         src_subrect, dst_size, callback, color_type);
   }
 }
 
 void RenderWidgetHostViewMac::CopyFromCompositingSurfaceToVideoFrame(
       const gfx::Rect& src_subrect,
       const scoped_refptr<media::VideoFrame>& target,
@@ skipping 2148 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