Move MimeTypeResourceHandler before ThrottlingResourceHandler

content/browser/loader/mime_type_resource_handler.h

Index: content/browser/loader/mime_type_resource_handler.h
diff --git a/content/browser/loader/mime_type_resource_handler.h b/content/browser/loader/mime_type_resource_handler.h
index f5581a6a8072522363e1f61e1030129b3ec9d4f2..94883a3de4acf64d91a43f1c898cd69b5a82fc2d 100644
--- a/content/browser/loader/mime_type_resource_handler.h
+++ b/content/browser/loader/mime_type_resource_handler.h
@@ -38,9 +38,8 @@ struct WebPluginInfo;
 // Before a request is sent, this ResourceHandler will also set an appropriate
 // Accept header on the request based on its ResourceType, if one isn't already
 // present.
-class CONTENT_EXPORT MimeTypeResourceHandler
-    : public LayeredResourceHandler,
-      public ResourceController {
+class CONTENT_EXPORT MimeTypeResourceHandler : public LayeredResourceHandler,
+                                               public ResourceController {
  public:
   // If ENABLE_PLUGINS is defined, |plugin_service| must not be NULL.
   MimeTypeResourceHandler(std::unique_ptr<ResourceHandler> next_handler,
@@ -50,10 +49,37 @@ class CONTENT_EXPORT MimeTypeResourceHandler
   ~MimeTypeResourceHandler() override;
 
  private:
+  enum State {
+    // Starting state of the MimeTypeResourceHandler. In this state, it is
+    // acting as a blind pass-through ResourceHandler.
+    STATE_STARTING,
+
+    // In this state, the MimeTypeResourceHandler is buffering the response
+    // data in read_buffer_.
+    STATE_BUFFERING,
+
+    // In this state, the request is paused and the MimeTypeResourceHandler is
+    // waiting to start the replay of the response to the downstream
+    // ResourceHandlers.
+    STATE_PROCESSING,
+
+    // In this state, the MimeTypeResourceHandler is replaying the buffered
+    // OnResponseStarted event to the downstream ResourceHandlers.
+    STATE_REPLAYING_RESPONSE_RECEIVED,
+
+    // In this state, the MimeTypeResourceHandler is replaying the buffered
+    // OnResponseStarted event to the new leaf handler, if there is one.
+    STATE_REPLAYING_RESPONSE_RECEIVED_NEW_HANDLER,
+
+    // In this state, the MimeTypeResourceHandler is just a blind pass-through
+    // ResourceHandler.
+    STATE_STREAMING,
+  };
+
   // ResourceHandler implementation:
   void SetController(ResourceController* controller) override;
-  bool OnResponseStarted(ResourceResponse* response, bool* defer) override;
   bool OnWillStart(const GURL&, bool* defer) override;
+  bool OnResponseStarted(ResourceResponse* response, bool* defer) override;
   bool OnWillRead(scoped_refptr<net::IOBuffer>* buf,
                   int* buf_size,
                   int min_size) override;
@@ -62,13 +88,23 @@ class CONTENT_EXPORT MimeTypeResourceHandler
                            const std::string& security_info,
                            bool* defer) override;
 
+  // LayeredResourceHandler implementation:
+  void InstallNewLeafHandler(
+      std::unique_ptr<ResourceHandler> new_handler,
+      const std::string& payload_for_old_handler) override;
+
   // ResourceController implementation:
   void Resume() override;
   void Cancel() override;
   void CancelAndIgnore() override;
   void CancelWithError(int error_code) override;
 
-  bool ProcessResponse(bool* defer);
+  // Replays the buffered data to the downstream ResourceHandlers.
+  bool ProcessReplay(bool* defer);
+  bool MaybeStartReplay(bool* defer);
+  bool ReplayResponseReceived(bool* defer);
+  bool ReplayResponseReceivedNewHandler(bool* defer);
+  bool ReplayReadCompleted(bool* defer);
 
   bool ShouldSniffContent();
   bool DetermineMimeType();
@@ -85,50 +121,31 @@ class CONTENT_EXPORT MimeTypeResourceHandler
   bool UseAlternateNextHandler(std::unique_ptr<ResourceHandler> handler,
                                const std::string& payload_for_old_handler);
 
-  bool ReplayReadCompleted(bool* defer);
-  void CallReplayReadCompleted();
-
   bool MustDownload();
 
-  // Copies data from |read_buffer_| to |next_handler_|.
-  bool CopyReadBufferToNextHandler();
-
   // Called on the IO thread once the list of plugins has been loaded.
   void OnPluginsLoaded(const std::vector<WebPluginInfo>& plugins);
 
-  enum State {
-    STATE_STARTING,
-
-    // In this state, we are filling read_buffer_ with data for the purpose
-    // of sniffing the mime type of the response.
-    STATE_BUFFERING,
-
-    // In this state, we are select an appropriate downstream ResourceHandler
-    // based on the mime type of the response.  We are also potentially waiting
-    // for plugins to load so that we can determine if a plugin is available to
-    // handle the mime type.
-    STATE_PROCESSING,
-
-    // In this state, we are replaying buffered events (OnResponseStarted and
-    // OnReadCompleted) to the downstream ResourceHandler.
-    STATE_REPLAYING,
-
-    // In this state, we are just a blind pass-through ResourceHandler.
-    STATE_STREAMING
-  };
   State state_;
 
-  scoped_refptr<ResourceResponse> response_;
   ResourceDispatcherHostImpl* host_;
 #if defined(ENABLE_PLUGINS)
   PluginService* plugin_service_;
 #endif
+
+  bool must_download_;
+  bool must_download_is_set_;
+
+  // Used to buffer the reponse received until replay.
+  scoped_refptr<ResourceResponse> response_;
   scoped_refptr<net::IOBuffer> read_buffer_;
   int read_buffer_size_;
   int bytes_read_;
 
-  bool must_download_;
-  bool must_download_is_set_;
+  // Used to store a new leaf ResourceHandler until the actual one can be
+  // replaced during the replay of the reponse.
+  std::unique_ptr<ResourceHandler> new_leaf_handler_;
+  std::string payload_for_old_handler_;
 
   base::WeakPtrFactory<MimeTypeResourceHandler> weak_ptr_factory_;