[wip] Add canvas.toDataURL("image/png") compression control

Source/platform/graphics/GraphicsContextRecorder.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 696 matching lines @@
         default:
             ASSERT_NOT_REACHED();
             return "?";
         };
     }
 
     PassRefPtr<JSONObject> objectForBitmapData(const SkBitmap& bitmap)
     {
         RefPtr<JSONObject> dataItem = JSONObject::create();
         Vector<unsigned char> output;
-        WebCore::PNGImageEncoder::encode(bitmap, &output);
+        int compressionQuality = PNGImageEncoder::DefaultCompressionQuality;
+        WebCore::PNGImageEncoder::encode(bitmap, compressionQuality, &output);
         dataItem->setString("base64", WTF::base64Encode(reinterpret_cast<char*>(output.data()), output.size()));
         dataItem->setString("mimeType", "image/png");
         return dataItem.release();
     }
 
     PassRefPtr<JSONObject> objectForSkBitmap(const SkBitmap& bitmap)
     {
         RefPtr<JSONObject> bitmapItem = JSONObject::create();
         bitmapItem->setNumber("width", bitmap.width());
         bitmapItem->setNumber("height", bitmap.height());
@@ skipping 307 matching lines @@
 
 PassRefPtr<JSONArray> GraphicsContextSnapshot::snapshotCommandLog() const
 {
     LoggingCanvas canvas;
     FragmentSnapshotPlayer player(m_picture, &canvas);
     player.play(0, 0);
     return canvas.log();
 }
 
 }