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

chrome/browser/ui/android/context_menu_helper.cc

 // 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.
 
 #include "chrome/browser/ui/android/context_menu_helper.h"
 
 #include <stdint.h>
 
 #include <vector>
 
@@ skipping 220 matching lines @@
       content::RenderFrameHost::FromID(render_process_id_, render_frame_id_);
   if (!render_frame_host)
     return;
 
   chrome::mojom::ThumbnailCapturerPtr thumbnail_capturer;
   render_frame_host->GetRemoteInterfaces()->GetInterface(&thumbnail_capturer);
   // Bind the InterfacePtr into the callback so that it's kept alive
   // until there's either a connection error or a response.
   auto* thumbnail_capturer_proxy = thumbnail_capturer.get();
   thumbnail_capturer_proxy->RequestThumbnailForContextNode(
-      0, gfx::Size(max_dimen_px, max_dimen_px),
+      0, gfx::Size(max_dimen_px, max_dimen_px), chrome::mojom::ImageFormat::PNG,
       base::Bind(retrieve_callback, base::Passed(&thumbnail_capturer),
                  base::android::ScopedJavaGlobalRef<jobject>(env, jcallback)));
 }
 
 bool RegisterContextMenuHelper(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }