Add buffering to MimeSniffingResourceHandler.

content/browser/loader/intercepting_resource_handler.h

Index: content/browser/loader/intercepting_resource_handler.h
diff --git a/content/browser/loader/intercepting_resource_handler.h b/content/browser/loader/intercepting_resource_handler.h
index cbfbba4f99cf55a3b77020416ae06499baa6bb1c..d30776660f356a66b7978ed63907845daecd9ca7 100644
--- a/content/browser/loader/intercepting_resource_handler.h
+++ b/content/browser/loader/intercepting_resource_handler.h
@@ -56,9 +56,11 @@ class CONTENT_EXPORT InterceptingResourceHandler
 
   // Replaces the next handler with |new_handler|, sending
   // |payload_for_old_handler| to the old handler. Must be called after
-  // OnWillStart and OnRequestRedirected and before OnResponseStarted. One
-  // OnWillRead call is permitted beforehand. |new_handler|'s OnWillStart and
-  // OnRequestRedirected methods will not be called.
+  // OnWillStart and OnRequestRedirected and before OnResponseStarted.
+  // OnWillRead may not be called be called before this call. |new_handler|'s
+  // OnRequestRedirected method will not be called.  |new_handler|'s
+  // OnWillStart() method will be called following the call to
+  // InterceptingResourceHandler::OnResponseStarted.
   void UseNewHandler(std::unique_ptr<ResourceHandler> new_handler,
                      const std::string& payload_for_old_handler);
 
@@ -82,12 +84,6 @@ class CONTENT_EXPORT InterceptingResourceHandler
     // handlers.
     SWAPPING_HANDLERS,
 
-    // States where the InterceptingResourceHandler passes the initial
-    // OnWillRead call to the old handler, and then waits for the resulting
-    // buffer read buffer.
-    SENDING_ON_WILL_READ_TO_OLD_HANDLER,
-    WAITING_FOR_OLD_HANDLERS_BUFFER,
-
     // The InterceptingResourceHandler is sending the payload given via
     // UseNewHandler to the old handler. The first state starts retrieving a
     // buffer from the old handler, the second state copies as much of the data
@@ -98,26 +94,9 @@ class CONTENT_EXPORT InterceptingResourceHandler
     // The InterceptingResourcHandler is calling the new handler's
     // OnResponseStarted method and waiting for its completion via Resume().
     // After completion, the InterceptingResourceHandler will transition to
-    // SENDING_ON_RESPONSE_STARTED_TO_NEW_HANDLER on success.
+    // PASS_THROUGH on success.
     SENDING_ON_WILL_START_TO_NEW_HANDLER,
 
-    // The InterceptingResourcHandler is calling the new handler's
-    // OnResponseStarted method and waiting for its completion via Resume().
-    // After completion, the InterceptingResourceHandler will transition to
-    // WAITING_FOR_ON_READ_COMPLETED on success.
-    SENDING_ON_RESPONSE_STARTED_TO_NEW_HANDLER,
-
-    // The InterceptingResourcHandler is waiting for OnReadCompleted to be
-    // called.
-    WAITING_FOR_ON_READ_COMPLETED,
-
-    // The two phases of uploading previously received data stored in
-    // |first_read_buffer_double_| to the new handler, which is now stored in
-    // |next_handler_|. The first state gets a buffer to write to, and the next
-    // copies all the data it can to that buffer.
-    SENDING_BUFFER_TO_NEW_HANDLER,
-    SENDING_BUFFER_TO_NEW_HANDLER_WAITING_FOR_BUFFER,
-
     // The InterceptingResourceHandler has replaced its next ResourceHandler if
     // needed, and has ensured the buffered read data was properly transmitted
     // to the new ResourceHandler. The InterceptingResourceHandler now acts as
@@ -135,7 +114,6 @@ class CONTENT_EXPORT InterceptingResourceHandler
   void SendOnResponseStartedToOldHandler();
   void SendPayloadToOldHandler();
   void ReceivedBufferFromOldHandler();
-  void SendFirstReadBufferToNewHandler();
   void SendOnResponseStartedToNewHandler();
   void ReceivedBufferFromNewHandler();
 
@@ -145,27 +123,9 @@ class CONTENT_EXPORT InterceptingResourceHandler
   std::string payload_for_old_handler_;
   size_t payload_bytes_written_ = 0;
 
-  // Result of the first read, that may have to be passed to an alternate
-  // ResourceHandler instead of the original ResourceHandler.
-  scoped_refptr<net::IOBuffer> first_read_buffer_;
-  // Instead of |first_read_buffer_|, this handler creates a new IOBuffer with
-  // the same size and return it to the client.
-  scoped_refptr<net::IOBuffer> first_read_buffer_double_;
-  int first_read_buffer_size_ = 0;
-  int first_read_buffer_bytes_read_ = 0;
-  int first_read_buffer_bytes_written_ = 0;
-
-  // Information about the new handler's buffer while copying data from
-  // |first_read_buffer_double_| to the new handler's buffer.
-  // Note that when these are used, the old handler has been destroyed, and
-  // |next_handler_| is now the new one.
-  scoped_refptr<net::IOBuffer> new_handler_read_buffer_;
-  int new_handler_read_buffer_size_ = 0;
-
-  // Pointers to parent-owned read buffer and its size.  Only used for first
-  // OnWillRead call.
-  scoped_refptr<net::IOBuffer>* parent_read_buffer_ = nullptr;
-  int* parent_read_buffer_size_ = nullptr;
+  // Buffer pointers used for passing a payload to the old handler.
+  scoped_refptr<net::IOBuffer> read_buffer_;
+  int read_buffer_size_ = 0;
 
   scoped_refptr<ResourceResponse> response_;