Force image-decoding before resolving createImageBitmap promise

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 117 matching lines @@
             return nullptr;
         decoder->setData(image->data(), true);
         skiaImage = ImageBitmap::getSkImageFromDecoder(decoder.release());
         if (!skiaImage)
             return nullptr;
     }
 
     if (cropRect == srcRect) {
         if (flipY)
             return StaticBitmapImage::create(flipSkImageVertically(skiaImage->newSubset(srcRect), premultiplyAlpha ? PremultiplyAlpha : DontPremultiplyAlpha));
-        return StaticBitmapImage::create(adoptRef(skiaImage->newSubset(srcRect)));
+        SkImage* croppedSkImage = skiaImage->newSubset(srcRect);
+        if (cropRect == imgRect) {
+            SkImageInfo info = SkImageInfo::MakeN32(image->width(), image->height(), premultiplyAlpha ? kPremul_SkAlphaType : kUnpremul_SkAlphaType);
+            OwnPtr<uint8_t[]> imagePixels = copySkImageData(croppedSkImage, info);

[Justin Novosad, 2016/03/17 21:27:21]

Making a full copy, only to discard it after is wasteful. I understand that the
skia API is too opaque to trigger an immediate decode by any other means, but I
think you could read just a 1x1 pixel subregion.

+
+        }
+        return StaticBitmapImage::create(adoptRef(croppedSkImage));
     }
 
     RefPtr<SkSurface> surface = adoptRef(SkSurface::NewRasterN32Premul(cropRect.width(), cropRect.height()));
     if (!surface)
         return nullptr;
     if (srcRect.isEmpty())
         return StaticBitmapImage::create(adoptRef(surface->newImageSnapshot()));
 
     SkScalar dstLeft = std::min(0, -cropRect.x());
     SkScalar dstTop = std::min(0, -cropRect.y());
@@ skipping 297 matching lines @@
 FloatSize ImageBitmap::elementSize(const FloatSize&) const
 {
     return FloatSize(width(), height());
 }
 
 DEFINE_TRACE(ImageBitmap)
 {
 }
 
 } // namespace blink