Eliminate copies of encoded image data

third_party/WebKit/Source/platform/graphics/gpu/WebGLImageConversion.cpp

 // Copyright 2014 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 "platform/graphics/gpu/WebGLImageConversion.h"
 
 #include "platform/CheckedInt.h"
 #include "platform/graphics/ImageObserver.h"
 #include "platform/graphics/cpu/arm/WebGLImageConversionNEON.h"
 #include "platform/graphics/cpu/x86/WebGLImageConversionSSE.h"
 #include "platform/image-decoders/ImageDecoder.h"
+#include "platform/image-decoders/SharedBufferSegmentReader.h"
 #include "third_party/skia/include/core/SkImage.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 namespace {
 
 const float maxInt8Value = INT8_MAX;
 const float maxUInt8Value = UINT8_MAX;
@@ skipping 2043 matching lines @@
 
     RefPtr<SkImage> skiaImage = m_image->imageForCurrentFrame();
     SkImageInfo info = skiaImage
         ? SkImageInfo::MakeN32Premul(m_image->width(), m_image->height())
         : SkImageInfo::MakeUnknown();
     m_alphaOp = AlphaDoNothing;
     bool hasAlpha = skiaImage ? !skiaImage->isOpaque() : true;
 
     if ((!skiaImage || ignoreGammaAndColorProfile || (hasAlpha && !premultiplyAlpha)) && m_image->data()) {
         // Attempt to get raw unpremultiplied image data.
+        RefPtr<SharedBufferSegmentReader> segmentReader = adoptRef(new SharedBufferSegmentReader(m_image->data()));
         OwnPtr<ImageDecoder> decoder(ImageDecoder::create(
-            *(m_image->data()), ImageDecoder::AlphaNotPremultiplied,
+            *segmentReader.get(), ImageDecoder::AlphaNotPremultiplied,
             ignoreGammaAndColorProfile ? ImageDecoder::GammaAndColorProfileIgnored : ImageDecoder::GammaAndColorProfileApplied));
         if (!decoder)
             return;
-        decoder->setData(m_image->data(), true);
+        decoder->setData(segmentReader.get(), true);
         if (!decoder->frameCount())
             return;
         ImageFrame* frame = decoder->frameBufferAtIndex(0);
         if (!frame || frame->status() != ImageFrame::FrameComplete)
             return;
         hasAlpha = frame->hasAlpha();
         SkBitmap bitmap = frame->bitmap();
         if (!frameIsValid(bitmap))
             return;
 
@@ skipping 240 matching lines @@
     }
 
     FormatConverter converter(width, height, sourceData, destinationData, srcStride, dstStride);
     converter.convert(sourceDataFormat, dstDataFormat, alphaOp);
     if (!converter.Success())
         return false;
     return true;
 }
 
 } // namespace blink