Phase II Step 3: Reload LoFi/placeholder images via new ImageResource

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

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
     rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 98 matching lines @@
     kReloadAlways,
   };
 
   virtual ~Resource();
 
   DECLARE_VIRTUAL_TRACE();
 
   virtual void setEncoding(const String&) {}
   virtual String encoding() const { return String(); }
   virtual void appendData(const char*, size_t);
-  virtual void error(const ResourceError&);
+  // LoFi images can be reloaded using |fetcherForReload| (if non-null).
+  virtual void error(const ResourceError&,
+                     ResourceFetcher* fetcherForReload = nullptr);
   virtual void setCORSFailed() {}
 
   void setNeedsSynchronousCacheHit(bool needsSynchronousCacheHit) {
     m_needsSynchronousCacheHit = needsSynchronousCacheHit;
   }
 
   void setLinkPreload(bool isLinkPreload) { m_linkPreload = isLinkPreload; }
   bool isLinkPreload() const { return m_linkPreload; }
 
   void setPreloadDiscoveryTime(double preloadDiscoveryTime) {
@@ skipping 74 matching lines @@
 
   void setLoader(ResourceLoader*);
   ResourceLoader* loader() const { return m_loader.get(); }
 
   virtual bool isImage() const { return false; }
   bool shouldBlockLoadEvent() const;
   bool isLoadEventBlockingResourceType() const;
 
   // Computes the status of an object after loading. Updates the expire date on
   // the cache entry file
-  virtual void finish(double finishTime);
+  // LoFi images can be reloaded using |fetcherForReload| (if non-null).
+  virtual void finish(double finishTime,
+                      ResourceFetcher* fetcherForReload = nullptr);
   void finish() { finish(0.0); }
 
   // FIXME: Remove the stringless variant once all the callsites' error messages
   // are updated.
   bool passesAccessControlCheck(SecurityOrigin*) const;
   bool passesAccessControlCheck(SecurityOrigin*,
                                 String& errorDescription) const;
 
   virtual PassRefPtr<const SharedBuffer> resourceBuffer() const {
     return m_data;
@@ skipping 112 matching lines @@
 
   // Used by the MemoryCache to reduce the memory consumption of the entry.
   void prune();
 
   virtual void onMemoryDump(WebMemoryDumpLevelOfDetail,
                             WebProcessMemoryDump*) const;
 
   // If this Resource is ImageResource and has the Lo-Fi response headers or is
   // a placeholder, reload the full original image with the Lo-Fi state set to
   // off and optionally bypassing the cache.
-  virtual void reloadIfLoFiOrPlaceholderImage(ResourceFetcher*,
-                                              ReloadLoFiOrPlaceholderPolicy) {}
+  // If reloading is started, this method returns a new Resource that is used
+  // for reloading, and |this| should be no longer used.
+  // Otherwise, this method returns nullptr.
+  virtual Resource* reloadIfLoFiOrPlaceholderImage(

[Nate Chapin, 2016/12/28 00:14:57]

Can we delete this from Resource entirely? It seems like it should be
non-virtual and just live on ImageResource.

[hiroshige, 2016/12/28 01:04:21]

This virtual method would remain after this CL for
ResourceFetcher::reloadLoFiImages() to prevent direct dependencies from
ResourceFetcher to ImageResource.
(I also would like to remove this but currently have no good idea)

+      ResourceFetcher*,
+      ReloadLoFiOrPlaceholderPolicy) {
+    return nullptr;
+  }
 
   static const char* resourceTypeToString(Type, const FetchInitiatorInfo&);
 
  protected:
   Resource(const ResourceRequest&, Type, const ResourceLoaderOptions&);
 
   virtual void checkNotify();
 
   void markClientFinished(ResourceClient*);
 
@@ skipping 35 matching lines @@
 
   virtual void destroyDecodedDataIfPossible() {}
 
   // Returns the memory dump name used for tracing. See Resource::onMemoryDump.
   String getMemoryDumpName() const;
 
   const HeapHashCountedSet<WeakMember<ResourceClient>>& clients() const {
     return m_clients;
   }
 
-  void setCachePolicyBypassingCache();
-  void setLoFiStateOff();
-  void clearRangeRequestHeader();
-
   SharedBuffer* data() const { return m_data.get(); }
   void clearData();
 
   class ProhibitAddRemoveClientInScope : public AutoReset<bool> {
    public:
     ProhibitAddRemoveClientInScope(Resource* resource)
         : AutoReset(&resource->m_isAddRemoveClientProhibited, true) {}
   };
 
  private:
@@ skipping 87 matching lines @@
 };
 
 #define DEFINE_RESOURCE_TYPE_CASTS(typeName)                   \
   DEFINE_TYPE_CASTS(typeName##Resource, Resource, resource,    \
                     resource->getType() == Resource::typeName, \
                     resource.getType() == Resource::typeName);
 
 }  // namespace blink
 
 #endif