Remove duplication of encoded image data

third_party/WebKit/Source/core/fetch/ImageResource.h

Index: third_party/WebKit/Source/core/fetch/ImageResource.h
diff --git a/third_party/WebKit/Source/core/fetch/ImageResource.h b/third_party/WebKit/Source/core/fetch/ImageResource.h
index 412c3a4c15d93cbcae5f7f8f8dd8d71024a5a798..9e23791f6d994e83c95fc5153a04cf7c40111463 100644
--- a/third_party/WebKit/Source/core/fetch/ImageResource.h
+++ b/third_party/WebKit/Source/core/fetch/ImageResource.h
@@ -44,6 +44,10 @@ class ResourceClient;
 class ResourceFetcher;
 class SecurityOrigin;
 
+// ImageResource class represents an image type resource.
+//
+// As for the lifetimes of m_image and m_data, see this document:
+// https://docs.google.com/document/d/1v0yTAZ6wkqX2U_M6BNIGUJpM1s0TIw1VsqpxoL7aciY/edit?usp=sharing
 class CORE_EXPORT ImageResource final : public Resource, public ImageObserver, public MultipartImageResourceParser::Client {
     friend class MemoryCache;
     USING_GARBAGE_COLLECTED_MIXIN(ImageResource);
@@ -101,6 +105,7 @@ public:
 
     void allClientsAndObserversRemoved() override;
 
+    PassRefPtr<SharedBuffer> resourceBuffer() const override;
     void appendData(const char*, size_t) override;
     void error(const ResourceError&) override;
     void responseReceived(const ResourceResponse&, std::unique_ptr<WebDataConsumerHandle>) override;