Cheaper thread-safe atomic initialization of static references.

Source/platform/graphics/ImageFrameGenerator.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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 76 matching lines @@
     , m_isMultiFrame(isMultiFrame)
     , m_decodeFailedAndEmpty(false)
     , m_decodeCount(0)
     , m_frameCount(0)
 {
     setData(data.get(), allDataReceived);
 }
 
 ImageFrameGenerator::~ImageFrameGenerator()
 {
-    ImageDecodingStore::instance()->removeCacheIndexedByGenerator(this);
+    ImageDecodingStore::instance().removeCacheIndexedByGenerator(this);
 }
 
 void ImageFrameGenerator::setData(PassRefPtr<SharedBuffer> data, bool allDataReceived)
 {
     m_data.setData(data.get(), allDataReceived);
 }
 
 void ImageFrameGenerator::copyData(RefPtr<SharedBuffer>* data, bool* allDataReceived)
 {
     SharedBuffer* buffer = 0;
@@ skipping 79 matching lines @@
     if (yuvDecoded)
         setHasAlpha(0, false); // YUV is always opaque
     return yuvDecoded;
 }
 
 SkBitmap ImageFrameGenerator::tryToResumeDecode(const SkISize& scaledSize, size_t index)
 {
     TRACE_EVENT1("blink", "ImageFrameGenerator::tryToResumeDecodeAndScale", "index", static_cast<int>(index));
 
     ImageDecoder* decoder = 0;
-    const bool resumeDecoding = ImageDecodingStore::instance()->lockDecoder(this, m_fullSize, &decoder);
+    const bool resumeDecoding = ImageDecodingStore::instance().lockDecoder(this, m_fullSize, &decoder);
     ASSERT(!resumeDecoding || decoder);
 
     SkBitmap fullSizeImage;
     bool complete = decode(index, &decoder, &fullSizeImage);
 
     if (!decoder)
         return SkBitmap();
     if (index >= m_frameComplete.size())
         m_frameComplete.resize(index + 1);
     m_frameComplete[index] = complete;
 
     // If we are not resuming decoding that means the decoder is freshly
     // created and we have ownership. If we are resuming decoding then
     // the decoder is owned by ImageDecodingStore.
     OwnPtr<ImageDecoder> decoderContainer;
     if (!resumeDecoding)
         decoderContainer = adoptPtr(decoder);
 
     if (fullSizeImage.isNull()) {
         // If decode has failed and resulted an empty image we can save work
         // in the future by returning early.
         m_decodeFailedAndEmpty = !m_isMultiFrame && decoder->failed();
 
         if (resumeDecoding)
-            ImageDecodingStore::instance()->unlockDecoder(this, decoder);
+            ImageDecodingStore::instance().unlockDecoder(this, decoder);
         return SkBitmap();
     }
 
     // If the image generated is complete then there is no need to keep
     // the decoder. For multi-frame images, if all frames in the image are
     // decoded, we remove the decoder.
     bool removeDecoder;
 
     if (m_isMultiFrame) {
         size_t decodedFrameCount = 0;
         for (Vector<bool>::iterator it = m_frameComplete.begin(); it != m_frameComplete.end(); ++it) {
             if (*it)
                 decodedFrameCount++;
         }
         removeDecoder = m_frameCount && (decodedFrameCount == m_frameCount);
     } else {
         removeDecoder = complete;
     }
 
     if (resumeDecoding) {
         if (removeDecoder) {
-            ImageDecodingStore::instance()->removeDecoder(this, decoder);
+            ImageDecodingStore::instance().removeDecoder(this, decoder);
             m_frameComplete.clear();
+        } else {
+            ImageDecodingStore::instance().unlockDecoder(this, decoder);
         }
-        else
-            ImageDecodingStore::instance()->unlockDecoder(this, decoder);
     } else if (!removeDecoder) {
-        ImageDecodingStore::instance()->insertDecoder(this, decoderContainer.release());
+        ImageDecodingStore::instance().insertDecoder(this, decoderContainer.release());
     }
     return fullSizeImage;
 }
 
 void ImageFrameGenerator::setHasAlpha(size_t index, bool hasAlpha)
 {
     MutexLocker lock(m_alphaMutex);
     if (index >= m_hasAlpha.size()) {
         const size_t oldSize = m_hasAlpha.size();
         m_hasAlpha.resize(index + 1);
@@ skipping 96 matching lines @@
 
     // Setting a dummy ImagePlanes object signals to the decoder that we want to do YUV decoding.
     decoder->setData(data, allDataReceived);
     OwnPtr<ImagePlanes> dummyImagePlanes = adoptPtr(new ImagePlanes);
     decoder->setImagePlanes(dummyImagePlanes.release());
 
     return updateYUVComponentSizes(decoder.get(), componentSizes, ImageDecoder::SizeForMemoryAllocation);
 }
 
 } // namespace blink