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

extensions/browser/api/web_contents_capture_client.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 "extensions/browser/api/web_contents_capture_client.h"
 
 #include "base/base64.h"
 #include "base/strings/stringprintf.h"
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/render_widget_host_view.h"
@@ skipping 89 matching lines @@
   }
   OnCaptureFailure(FAILURE_REASON_UNKNOWN);
 }
 
 // TODO(wjmaclean) can this be static?
 bool WebContentsCaptureClient::EncodeBitmap(const SkBitmap& bitmap,
                                             std::string* base64_result) {
   DCHECK(base64_result);
   std::vector<unsigned char> data;
   SkAutoLockPixels screen_capture_lock(bitmap);
+  const bool should_discard_alpha = !ClientAllowsTransparency();
   bool encoded = false;
   std::string mime_type;
   switch (image_format_) {
     case api::extension_types::IMAGE_FORMAT_JPEG:
       encoded = gfx::JPEGCodec::Encode(
           reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0)),
           gfx::JPEGCodec::FORMAT_SkBitmap, bitmap.width(), bitmap.height(),
           static_cast<int>(bitmap.rowBytes()), image_quality_, &data);
       mime_type = kMimeTypeJpeg;
       break;
     case api::extension_types::IMAGE_FORMAT_PNG:
-      encoded =
-          gfx::PNGCodec::EncodeBGRASkBitmap(bitmap,
-                                            true,  // Discard transparency.
-                                            &data);
+      encoded = gfx::PNGCodec::EncodeBGRASkBitmap(bitmap, should_discard_alpha,
+                                                  &data);
       mime_type = kMimeTypePng;
       break;
     default:
       NOTREACHED() << "Invalid image format.";
   }
 
   if (!encoded)
     return false;
 
   base::StringPiece stream_as_string(reinterpret_cast<const char*>(data.data()),
                                      data.size());
 
   base::Base64Encode(stream_as_string, base64_result);
   base64_result->insert(
       0, base::StringPrintf("data:%s;base64,", mime_type.c_str()));
 
   return true;
 }
 
 }  // namespace extensions