Fix dead-lock issue attempting to decode

third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp

 /*
  * Copyright (C) 2012 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 36 matching lines @@
 }
 
 DecodingImageGenerator::~DecodingImageGenerator()
 {
 }
 
 SkData* DecodingImageGenerator::onRefEncodedData(GrContext* ctx)
 {
     TRACE_EVENT0("blink", "DecodingImageGenerator::refEncodedData");
 
-    return m_allDataReceived ? m_data->getAsSkData().leakRef() : nullptr;
+    // The GPU only wants the data if it has all been received, since the GPU
+    // only wants a complete texture. getAsSkData() may require copying, so
+    // skip it and just return nullptr to avoid a slowdown. (See
+    // crbug.com/568016 for details about such a slowdown.)
+    // TODO (scroggo): Stop relying on the internal knowledge of how Skia uses
+    // this. skbug.com/5485
+    if (ctx && !m_allDataReceived)
+        return nullptr;
+
+    // Other clients are serializers, which want the data even if it requires
+    // copying, and even if the data is incomplete. (Otherwise they would
+    // potentially need to decode the partial image in order to re-encode it.)
+    return m_data->getAsSkData().leakRef();
 }
 
 bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, SkPMColor table[], int* tableCount)
 {
     TRACE_EVENT1("blink", "DecodingImageGenerator::getPixels", "frame index", static_cast<int>(m_frameIndex));
 
     // Implementation doesn't support scaling yet so make sure we're not given a different size.
     if (info.width() != getInfo().width() || info.height() != getInfo().height())
         return false;
 
@@ skipping 58 matching lines @@
     const SkImageInfo info = SkImageInfo::MakeN32Premul(size.width(), size.height());
 
     RefPtr<ImageFrameGenerator> frame = ImageFrameGenerator::create(SkISize::Make(size.width(), size.height()), false);
     if (!frame)
         return 0;
 
     return new DecodingImageGenerator(frame, info, segmentReader.release(), true, 0);
 }
 
 } // namespace blink