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

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

Index: third_party/WebKit/Source/core/fetch/Resource.h
diff --git a/third_party/WebKit/Source/core/fetch/Resource.h b/third_party/WebKit/Source/core/fetch/Resource.h
index 22156e870a5b175f8344bbc590c731bc1962495c..8dec08cf8da49989e254802c776107251b7e46b3 100644
--- a/third_party/WebKit/Source/core/fetch/Resource.h
+++ b/third_party/WebKit/Source/core/fetch/Resource.h
@@ -116,7 +116,9 @@ class CORE_EXPORT Resource : public GarbageCollectedFinalized<Resource>,
   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) {
@@ -211,7 +213,9 @@ class CORE_EXPORT Resource : public GarbageCollectedFinalized<Resource>,
 
   // 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
@@ -344,8 +348,14 @@ class CORE_EXPORT Resource : public GarbageCollectedFinalized<Resource>,
   // 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&);
 
@@ -401,10 +411,6 @@ class CORE_EXPORT Resource : public GarbageCollectedFinalized<Resource>,
     return m_clients;
   }
 
-  void setCachePolicyBypassingCache();
-  void setLoFiStateOff();
-  void clearRangeRequestHeader();
-
   SharedBuffer* data() const { return m_data.get(); }
   void clearData();