Fixing transparent pixels appearing black when rendered for the context menu.

chrome/renderer/chrome_render_frame_observer.h

 // Copyright 2013 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 CHROME_RENDERER_CHROME_RENDER_FRAME_OBSERVER_H_
 #define CHROME_RENDERER_CHROME_RENDER_FRAME_OBSERVER_H_
 
 #include "base/macros.h"
 #include "base/timer/timer.h"
 #include "chrome/common/image_context_menu_renderer.mojom.h"
@@ skipping 37 matching lines @@
   void DidMeaningfulLayout(blink::WebMeaningfulLayout layout_type) override;
   void OnDestruct() override;
 
   // chrome::mojom::ImageContextMenuRenderer:
   void RequestReloadImageForContextNode() override;
 
   // chrome::mojom::ThumbnailCapturer:
   void RequestThumbnailForContextNode(
       int32_t thumbnail_min_area_pixels,
       const gfx::Size& thumbnail_max_size_pixels,
+      bool use_png_codec,
       const RequestThumbnailForContextNodeCallback& callback) override;
 
   // Mojo handlers.
   void OnImageContextMenuRendererRequest(
       const service_manager::BindSourceInfo& source_info,
       chrome::mojom::ImageContextMenuRendererRequest request);
   void OnThumbnailCapturerRequest(
       const service_manager::BindSourceInfo& source_info,
       chrome::mojom::ThumbnailCapturerRequest request);
 
@@ skipping 23 matching lines @@
   mojo::BindingSet<chrome::mojom::ImageContextMenuRenderer>
       image_context_menu_renderer_bindings_;
 
   mojo::BindingSet<chrome::mojom::ThumbnailCapturer>
       thumbnail_capturer_bindings_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeRenderFrameObserver);
 };
 
 #endif  // CHROME_RENDERER_CHROME_RENDER_FRAME_OBSERVER_H_