Image decoding: Remove deprecated image caching code

Source/platform/graphics/ImageFrameGeneratorTest.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 40 matching lines @@
     return info;
 }
 
 } // namespace
 
 class ImageFrameGeneratorTest : public ::testing::Test, public MockImageDecoderClient {
 public:
     virtual void SetUp() OVERRIDE
     {
         ImageDecodingStore::instance()->setCacheLimitInBytes(1024 * 1024);
-        ImageDecodingStore::instance()->setImageCachingEnabled(true);
         m_data = SharedBuffer::create();
         m_generator = ImageFrameGenerator::create(fullSize(), m_data, false);
         useMockImageDecoderFactory();
         m_decodersDestroyed = 0;
         m_frameBufferRequestCount = 0;
         m_status = ImageFrame::FrameEmpty;
     }
 
     virtual void TearDown() OVERRIDE
     {
@@ skipping 123 matching lines @@
     static_cast<MockImageDecoder*>(tempDecoder)->setFrameHasAlpha(false);
     ImageDecodingStore::instance()->unlockDecoder(m_generator.get(), tempDecoder);
 
     setFrameStatus(ImageFrame::FrameComplete);
     m_generator->decodeAndScale(imageInfo(), 1, buffer, 100 * 4);
     EXPECT_EQ(2, m_frameBufferRequestCount);
     EXPECT_FALSE(m_generator->hasAlpha(1));
 }
 
 } // namespace blink