Reland of: Revise the code for premultiplyAlpha=false for createImageBitmap(HTMLCanvasElement)

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 "core/frame/ImageBitmap.h"
 
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/ImageData.h"
 #include "platform/image-decoders/ImageDecoder.h"
@@ skipping 172 matching lines @@
     }
     m_image->setOriginClean(!video->wouldTaintOrigin(document->securityOrigin()));
 }
 
 ImageBitmap::ImageBitmap(HTMLCanvasElement* canvas, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
     ASSERT(canvas->isPaintable());
     bool imageOrientationFlipYFlag;
     bool premultiplyAlphaEnabledFlag;
     parseOptions(options, imageOrientationFlipYFlag, premultiplyAlphaEnabledFlag);
-    m_image = cropImage(canvas->copiedImage(BackBuffer, PreferAcceleration).get(), cropRect, imageOrientationFlipYFlag, premultiplyAlphaEnabledFlag);
+    // canvas is always premultiplied, so set the last parameter to true and convert to un-premul later
+    m_image = cropImage(canvas->copiedImage(BackBuffer, PreferAcceleration).get(), cropRect, imageOrientationFlipYFlag, true);
+    if (!premultiplyAlphaEnabledFlag)
+        m_image = StaticBitmapImage::create(premulSkImageToUnPremul(m_image->imageForCurrentFrame().get()));
     m_image->setOriginClean(canvas->originClean());
 }
 
 ImageBitmap::ImageBitmap(ImageData* data, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
     IntRect srcRect = intersection(cropRect, IntRect(IntPoint(), data->size()));
 
     OwnPtr<ImageBuffer> buffer = ImageBuffer::create(cropRect.size(), NonOpaque, DoNotInitializeImagePixels);
     if (!buffer)
         return;
@@ skipping 156 matching lines @@
 {
     return FloatSize(width(), height());
 }
 
 DEFINE_TRACE(ImageBitmap)
 {
     ImageLoaderClient::trace(visitor);
 }
 
 } // namespace blink