Fixing performance issue of creating imagebitmap from ImageData

third_party/WebKit/Source/core/frame/ImageBitmap.cpp

 // 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 "config.h"
 #include "core/frame/ImageBitmap.h"
 
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/ImageData.h"
@@ skipping 80 matching lines @@
     ASSERT(canvas->isPaintable());
     m_bitmap = cropImage(canvas->copiedImage(BackBuffer, PreferAcceleration), cropRect);
 }
 
 ImageBitmap::ImageBitmap(ImageData* data, const IntRect& cropRect)
     : m_imageElement(nullptr)
     , m_cropRect(cropRect)
     , m_bitmapOffset(IntPoint())
 {
     IntRect srcRect = intersection(cropRect, IntRect(IntPoint(), data->size()));
-    OwnPtr<ImageBuffer> buffer = ImageBuffer::create(data->size());
+    OwnPtr<ImageBuffer> buffer = ImageBuffer::create(data->size(), Opaque, DoNotInitializeImagePixels);
     if (!buffer)
         return;
 
     if (srcRect.width() > 0 && srcRect.height() > 0)
         buffer->putByteArray(Premultiplied, data->data()->data(), data->size(), srcRect, IntPoint(std::min(0, -cropRect.x()), std::min(0, -cropRect.y())));
 
     m_bitmap = buffer->newImageSnapshot();
     m_bitmapRect = IntRect(IntPoint(std::max(0, -cropRect.x()), std::max(0, -cropRect.y())),  srcRect.size());
 }
 
@@ skipping 108 matching lines @@
     return FloatSize(width(), height());
 }
 
 DEFINE_TRACE(ImageBitmap)
 {
     visitor->trace(m_imageElement);
     ImageLoaderClient::trace(visitor);
 }
 
 } // namespace blink