Make ResourceHandler::OnWillRead able to complete asynchronously.

content/browser/loader/mime_sniffing_resource_handler.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // 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_SNIFFING_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_LOADER_MIME_SNIFFING_RESOURCE_HANDLER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 48 matching lines @@
     // 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 these states, the MimeSniffingResourceHandler is calling OnWillRead on
+    // the downstream ResourceHandler and then waiting for the response.
+    STATE_CALLING_ON_WILL_READ,
+    STATE_WAITING_FOR_BUFFER,
+
     // 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 OnWillStart(const GURL&,
                    std::unique_ptr<ResourceController> controller) override;
   void OnResponseStarted(
       ResourceResponse* response,
       std::unique_ptr<ResourceController> controller) override;
-  bool OnWillRead(scoped_refptr<net::IOBuffer>* buf,
-                  int* buf_size) override;
+  void OnWillRead(scoped_refptr<net::IOBuffer>* buf,
+                  int* buf_size,
+                  std::unique_ptr<ResourceController> controller) override;
   void OnReadCompleted(int bytes_read,
                        std::unique_ptr<ResourceController> controller) override;
   void OnResponseCompleted(
       const net::URLRequestStatus& status,
       std::unique_ptr<ResourceController> controller) override;
 
   void ResumeInternal();
 
   // --------------------------------------------------------------------------
   // The following methods replay the buffered data to the downstream
   // ResourceHandlers. They return false if the request should be cancelled,
   // true otherwise. Each of them will set |defer| to true if the request will
   // proceed to the next stage asynchronously.
 
   // Used to advance through the states of the state machine.
   void AdvanceState();
 
   // Intercepts the request as a stream/download if needed.
   void MaybeIntercept();
 
+  // Calls OnWillRead on the downstream handlers.
+  void CallOnWillRead();
+
+  // Copies received buffer to parent.
+  void BufferReceived();
+
   // Replays OnResponseStarted on the downstream handlers.
   void ReplayResponseReceived();
 
   // Replays OnReadCompleted on the downstreams handlers.
   void ReplayReadCompleted();
 
   // --------------------------------------------------------------------------
 
   // Whether the response body should be sniffed in order to determine the MIME
   // type of the response.
@@ skipping 37 matching lines @@
 
   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_;
 
+  // Pointers to parent-owned read buffer and its size.  Only used for first
+  // OnWillRead call.
+  scoped_refptr<net::IOBuffer>* parent_read_buffer_;
+  int* parent_read_buffer_size_;
+
   // The InterceptingResourceHandler that will perform ResourceHandler swap if
   // needed.
   InterceptingResourceHandler* intercepting_handler_;
 
   RequestContextType request_context_type_;
 
   // True if current in an AdvanceState loop. Used to prevent re-entrancy and
   // avoid an extra PostTask.
   bool in_state_loop_;
   // Set to true if Resume() is called while |in_state_loop_| is true. When
   // returning to the parent AdvanceState loop, will synchronously advance to
   // the next state when control returns to the AdvanceState loop.
   bool advance_state_;
 
   base::WeakPtrFactory<MimeSniffingResourceHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MimeSniffingResourceHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_MIME_SNIFFING_RESOURCE_HANDLER_H_