net: Make UploadDataStream::Read() asynchronous

net/base/upload_file_element_reader.h

Index: net/base/upload_file_element_reader.h
diff --git a/net/base/upload_file_element_reader.h b/net/base/upload_file_element_reader.h
index cc8e83053a2979161ed6ad7931e0e4846b814a08..71fb3cc9564b9c492b389ca8535d885bb86c5736 100644
--- a/net/base/upload_file_element_reader.h
+++ b/net/base/upload_file_element_reader.h
@@ -31,7 +31,10 @@ class NET_EXPORT_PRIVATE UploadFileElementReader : public UploadElementReader {
   virtual int InitSync() OVERRIDE;
   virtual uint64 GetContentLength() const OVERRIDE;
   virtual uint64 BytesRemaining() const OVERRIDE;
-  virtual int ReadSync(char* buf, int buf_length) OVERRIDE;
+  virtual int Read(IOBuffer* buf,
+                   int buf_length,
+                   const CompletionCallback& callback) OVERRIDE;
+  virtual int ReadSync(IOBuffer* buf, int buf_length) OVERRIDE;
 
  private:
   // This method is used to implement Init().
@@ -40,6 +43,11 @@ class NET_EXPORT_PRIVATE UploadFileElementReader : public UploadElementReader {
                        int* result,
                        const CompletionCallback& callback);
 
+  // This method is used to implement Read().
+  void OnReadCompleted(scoped_ptr<FileStream> file_stream,
+                       int* result,
+                       const CompletionCallback& callback);
+
   // Sets an value to override the result for GetContentLength().
   // Used for tests.
   struct NET_EXPORT_PRIVATE ScopedOverridingContentLengthForTests {