Move MimeTypeResourceHandler before ThrottlingResourceHandler

content/browser/loader/mime_sniffing_resource_handler.h

Index: content/browser/loader/mime_sniffing_resource_handler.h
diff --git a/content/browser/loader/mime_type_resource_handler.h b/content/browser/loader/mime_sniffing_resource_handler.h
similarity index 52%
rename from content/browser/loader/mime_type_resource_handler.h
rename to content/browser/loader/mime_sniffing_resource_handler.h
index f5581a6a8072522363e1f61e1030129b3ec9d4f2..f0dd8ee1c658204a710630f30d5a81119a94b2ca 100644
--- a/content/browser/loader/mime_type_resource_handler.h
+++ b/content/browser/loader/mime_sniffing_resource_handler.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CONTENT_BROWSER_LOADER_MIME_TYPE_RESOURCE_HANDLER_H_
-#define CONTENT_BROWSER_LOADER_MIME_TYPE_RESOURCE_HANDLER_H_
+#ifndef CONTENT_BROWSER_LOADER_MIME_SNIFFING_RESOURCE_HANDLER_H_
+#define CONTENT_BROWSER_LOADER_MIME_SNIFFING_RESOURCE_HANDLER_H_
 
 #include <string>
 #include <vector>
@@ -19,15 +19,13 @@ class URLRequest;
 }
 
 namespace content {
+class InterceptingResourceHandler;
 class PluginService;
 class ResourceDispatcherHostImpl;
 struct WebPluginInfo;
 
 // ResourceHandler that, if necessary, buffers a response body without passing
 // it to the next ResourceHandler until it can perform mime sniffing on it.
-// Once a response's MIME type is known, initiates special handling of the
-// response if needed (starts downloads, sends data to some plugin types via a
-// special channel).
 //
 // Uses the buffer provided by the original event handler for buffering, and
 // continues to reuses it until it can determine the MIME type
@@ -38,22 +36,50 @@ 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
+class CONTENT_EXPORT MimeSniffingResourceHandler
     : public LayeredResourceHandler,
       public ResourceController {
  public:
-  // If ENABLE_PLUGINS is defined, |plugin_service| must not be NULL.
-  MimeTypeResourceHandler(std::unique_ptr<ResourceHandler> next_handler,
-                          ResourceDispatcherHostImpl* host,
-                          PluginService* plugin_service,
-                          net::URLRequest* request);
-  ~MimeTypeResourceHandler() override;
+  MimeSniffingResourceHandler(std::unique_ptr<ResourceHandler> next_handler,
+                              ResourceDispatcherHostImpl* host,
+                              PluginService* plugin_service,
+                              InterceptingResourceHandler* intercepting_handler,
+                              net::URLRequest* request);
+  ~MimeSniffingResourceHandler() override;
 
  private:
+  friend class MimeSniffingResourceHandlerTest;
+  enum State {
+    // Starting state of the MimeSniffingResourceHandler. In this state, it is
+    // acting as a blind pass-through ResourceHandler until the response is
+    // received.
+    STATE_STARTING,
+
+    // In this state, the MimeSniffingResourceHandler is buffering the response
+    // data in read_buffer_, waiting to sniff the mime type and make a choice
+    // about request interception.
+    STATE_BUFFERING,
+
+    // In this state, the MimeSniffingResourceHandler has identified the mime
+    // type and made a decision on whether the request should be intercepted or
+    // not. It is nows attempting to replay the response to downstream
+    // handlers.
+    STATE_INTERCEPTION_CHECK_DONE,
+
+    // In this state, the MimeSniffingResourceHandler is replaying the buffered
+    // OnResponseStarted event to the downstream ResourceHandlers.
+    STATE_REPLAYING_RESPONSE_RECEIVED,
+
+    // In this state, the MimeSniffingResourceHandler 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;
@@ -68,73 +94,67 @@ class CONTENT_EXPORT MimeTypeResourceHandler
   void CancelAndIgnore() override;
   void CancelWithError(int error_code) override;
 
-  bool ProcessResponse(bool* defer);
+  // Replays the buffered data to the downstream ResourceHandlers.
+  void ProceedWithReplay();

[mmenke, 2016/08/26 21:03:04]

Mind adding a comment that these return false if the request should be
cancelled, true otherwise, and set defer to true if the request will advance to
the next state asynchronously?

[clamy, 2016/09/01 23:19:41]

Done.

+  bool ProcessReplay(bool* defer);
+  bool MaybeCheckForInterception(bool* defer);
+  bool GetFinalMimeType(bool* defer);

[mmenke, 2016/08/26 21:03:04]

Need to document these (At least the new ones)

[clamy, 2016/09/01 23:19:41]

Done.

+  bool ReplayResponseReceived(bool* defer);
+  bool ReplayResponseReceivedNewHandler(bool* defer);
+  bool ReplayReadCompleted(bool* defer);
 
   bool ShouldSniffContent();
   bool DetermineMimeType();

[mmenke, 2016/08/26 21:03:04]

DetermineMimeType was removed.

[clamy, 2016/09/01 23:19:41]

Done.

-  // Determines whether a plugin will handle the current request, and if so,
-  // sets up the handler to direct the response to that plugin. Returns false
+
+  // Checks whether this request should be intercepted as a stream or a
+  // download.

[mmenke, 2016/08/26 21:03:04]

Does more than just check, actually sets up the new handler.  See also
suggestion about renaming.

[clamy, 2016/09/01 23:19:41]

Done.

+  bool CheckForInterception(bool* defer);

[mmenke, 2016/08/26 21:03:04]

Should document return value / defer

[clamy, 2016/09/01 23:19:41]

Done.

+
+  // Determines whether a plugin will handle the current reques. Returns false

[mmenke, 2016/08/26 21:03:04]

nit:  request

[clamy, 2016/09/01 23:19:41]

Done.

   // if there is an error and the request should be cancelled and true
   // otherwise. |defer| is set to true if plugin data is stale and needs to be
   // refreshed before the request can be handled (in this case the function
   // still returns true). If the request is directed to a plugin,
   // |handled_by_plugin| is set to true.
-  bool SelectPluginHandler(bool* defer, bool* handled_by_plugin);
-  // Returns false if the request should be cancelled.
-  bool SelectNextHandler(bool* defer);
-  bool UseAlternateNextHandler(std::unique_ptr<ResourceHandler> handler,
-                               const std::string& payload_for_old_handler);
+  bool CheckForPluginHandler(bool* defer, bool* handled_by_plugin);
 
-  bool ReplayReadCompleted(bool* defer);
-  void CallReplayReadCompleted();
+  // Whether this request is allowed to be intercepted as a download or a
+  // stream.
+  bool CanBeIntercepted();
 
-  bool MustDownload();
+  // Whether the response we received is not provisional.
+  bool CheckResponseIsNotProvisional();
 
-  // Copies data from |read_buffer_| to |next_handler_|.
-  bool CopyReadBufferToNextHandler();
+  bool MustDownload();
 
   // 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_;
+  // The InterceptingResourceHandler that will perform ResourceHandler swap if
+  // needed.
+  InterceptingResourceHandler* intercepting_handler_;
 
-  base::WeakPtrFactory<MimeTypeResourceHandler> weak_ptr_factory_;
+  base::WeakPtrFactory<MimeSniffingResourceHandler> weak_ptr_factory_;
 
-  DISALLOW_COPY_AND_ASSIGN(MimeTypeResourceHandler);
+  DISALLOW_COPY_AND_ASSIGN(MimeSniffingResourceHandler);
 };
 
 }  // namespace content
 
-#endif  // CONTENT_BROWSER_LOADER_MIME_TYPE_RESOURCE_HANDLER_H_
+#endif  // CONTENT_BROWSER_LOADER_MIME_SNIFFING_RESOURCE_HANDLER_H_