Remove redundant reading and writing of data about SharedBuffer.

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

Index: third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.h
diff --git a/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.h b/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.h
index aa9722d99854d22529cda2ca720a64f1c7681ab0..0b5633758ef981cbc59e1c791e12882e2a41a969 100644
--- a/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.h
+++ b/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.h
@@ -27,6 +27,7 @@
 #define DecodingImageGenerator_h
 
 #include "platform/PlatformExport.h"
+#include "platform/SharedBuffer.h"
 #include "platform/image-decoders/SegmentReader.h"
 #include "platform/wtf/Allocator.h"
 #include "platform/wtf/Noncopyable.h"
@@ -60,6 +61,14 @@ class PLATFORM_EXPORT DecodingImageGenerator final : public SkImageGenerator {
                          bool all_data_received,
                          size_t index,
                          uint32_t unique_id = kNeedNewImageUniqueID);
+
+  DecodingImageGenerator(PassRefPtr<ImageFrameGenerator>,
+                         const SkImageInfo&,
+                         PassRefPtr<SharedBuffer::ThreadSafeStepper>,
+                         bool all_data_received,
+                         size_t index,
+                         uint32_t unique_id = kNeedNewImageUniqueID);
+
   ~DecodingImageGenerator() override;
 
   void SetCanYUVDecode(bool yes) { can_yuv_decode_ = yes; }
@@ -77,8 +86,11 @@ class PLATFORM_EXPORT DecodingImageGenerator final : public SkImageGenerator {
   bool onGetYUV8Planes(const SkYUVSizeInfo&, void* planes[3]) override;
 
  private:
+  PassRefPtr<SegmentReader> encoded_data() const;
+
   RefPtr<ImageFrameGenerator> frame_generator_;
-  const RefPtr<SegmentReader> data_;  // Data source.
+  const RefPtr<SegmentReader> reader_;
+  const RefPtr<SharedBuffer::ThreadSafeStepper> stepper_;
   const bool all_data_received_;
   const size_t frame_index_;
   bool can_yuv_decode_;