<webview>: Fix missing transparency in captureVisibleRegion().

extensions/browser/api/guest_view/web_view/web_view_internal_api.cc

 // Copyright 2014 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 "extensions/browser/api/guest_view/web_view/web_view_internal_api.h"
 
 #include <utility>
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
@@ skipping 255 matching lines @@
       web_view_internal::CaptureVisibleRegion::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
   scoped_ptr<ImageDetails> image_details;
   if (args_->GetSize() > 1) {
     base::Value* spec = NULL;
     EXTENSION_FUNCTION_VALIDATE(args_->Get(1, &spec) && spec);
     image_details = ImageDetails::FromValue(*spec);
   }
 
+  is_guest_transparent_ = guest->allow_transparency();
   return CaptureAsync(guest->web_contents(), image_details.get(),
                       base::Bind(&WebViewInternalCaptureVisibleRegionFunction::
                                      CopyFromBackingStoreComplete,
                                  this));
 }
 bool WebViewInternalCaptureVisibleRegionFunction::IsScreenshotEnabled() {
   // TODO(wjmaclean): Is it ok to always return true here?
   return true;
 }
 
+bool WebViewInternalCaptureVisibleRegionFunction::ClientAllowsTransparency() {
+  return is_guest_transparent_;
+}
+
 void WebViewInternalCaptureVisibleRegionFunction::OnCaptureSuccess(
     const SkBitmap& bitmap) {
   std::string base64_result;
   if (!EncodeBitmap(bitmap, &base64_result)) {
     OnCaptureFailure(FAILURE_REASON_ENCODING_FAILED);
     return;
   }
 
   SetResult(new base::StringValue(base64_result));
   SendResponse(true);
@@ skipping 655 matching lines @@
   // Will finish asynchronously.
   return true;
 }
 
 void WebViewInternalClearDataFunction::ClearDataDone() {
   Release();  // Balanced in RunAsync().
   SendResponse(true);
 }
 
 }  // namespace extensions