Add RGB565 Texture readback support in gl_helper

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 <QuartzCore/QuartzCore.h>
 
 #include "base/basictypes.h"
@@ skipping 1116 matching lines @@
 
 BackingStore* RenderWidgetHostViewMac::AllocBackingStore(
     const gfx::Size& size) {
   float scale = ScaleFactor(cocoa_view_);
   return new BackingStoreMac(render_widget_host_, size, scale);
 }
 
 void RenderWidgetHostViewMac::CopyFromCompositingSurface(
     const gfx::Rect& src_subrect,
     const gfx::Size& dst_size,
-    const base::Callback<void(bool, const SkBitmap&)>& callback) {
+    const base::Callback<void(bool, const SkBitmap&)>& callback,
+    bool readback_config_rgb565) {
+  if (readback_config_rgb565) {
+    NOTIMPLEMENTED();
+    callback.Run(false, SkBitmap());
+  }
   base::ScopedClosureRunner scoped_callback_runner(
       base::Bind(callback, false, SkBitmap()));
   float scale = ScaleFactor(cocoa_view_);
   gfx::Size dst_pixel_size = gfx::ToFlooredSize(
       gfx::ScaleSize(dst_size, scale));
   if (compositing_iosurface_ && compositing_iosurface_->HasIOSurface()) {
     ignore_result(scoped_callback_runner.Release());
     compositing_iosurface_->CopyTo(GetScaledOpenGLPixelRect(src_subrect),
                                    dst_pixel_size,
                                    callback);
@@ skipping 2835 matching lines @@
   return YES;
 }
 
 - (BOOL)isOpaque {
   if (renderWidgetHostView_->use_core_animation_)
     return YES;
   return [super isOpaque];
 }
 
 @end