net: Make UploadDataStream::Read() asynchronous

net/url_request/url_request.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 NET_URL_REQUEST_URL_REQUEST_H_
 #define NET_URL_REQUEST_URL_REQUEST_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 437 matching lines @@
   }
 
   // Returns the current load state for the request. |param| is an optional
   // parameter describing details related to the load state. Not all load states
   // have a parameter.
   LoadStateWithParam GetLoadState() const;
   void SetLoadStateParam(const string16& param) {
     load_state_param_ = param;
   }
 
-  // Returns the current upload progress in bytes.
+  // Returns the current upload progress in bytes. When the upload data is
+  // chunked, size is set to zero, but position will not be.
   UploadProgress GetUploadProgress() const;
 
   // Get response header(s) by ID or name.  These methods may only be called
   // once the delegate's OnResponseStarted method has been called.  Headers
   // that appear more than once in the response are coalesced, with values
   // separated by commas (per RFC 2616). This will not work with cookies since
   // comma can be used in cookie values.
   // TODO(darin): add API to enumerate response headers.
   void GetResponseHeaderById(int header_id, std::string* value);
   void GetResponseHeaderByName(const std::string& name, std::string* value);
@@ skipping 361 matching lines @@
   base::TimeTicks creation_time_;
 
   scoped_ptr<const base::debug::StackTrace> stack_trace_;
 
   DISALLOW_COPY_AND_ASSIGN(URLRequest);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_REQUEST_H_