Add a dummy variable to ResourceMsg_DataReceived.

content/common/resource_messages.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.
 
 // IPC messages for resource loading.
 //
 // NOTE: All messages must send an |int request_id| as their first parameter.
 
 // Multiply-included message file, hence no include guard.
 #include "base/memory/shared_memory.h"
@@ skipping 327 matching lines @@
 //
 IPC_MESSAGE_CONTROL4(ResourceMsg_SetDataBuffer,
                      int /* request_id */,
                      base::SharedMemoryHandle /* shm_handle */,
                      int /* shm_size */,
                      base::ProcessId /* renderer_pid */)
 
 // Sent when some data from a resource request is ready.  The data offset and
 // length specify a byte range into the shared memory buffer provided by the
 // SetDataBuffer message.
-IPC_MESSAGE_CONTROL4(ResourceMsg_DataReceived,
+// TODO(erikchen): This dummy variable is temporary and is only intended to be
+// present for one Canary release. http://crbug.com/527588.
+IPC_MESSAGE_CONTROL5(ResourceMsg_DataReceived,
                      int /* request_id */,
+                     int /* dummy variable */,
                      int /* data_offset */,
                      int /* data_length */,
                      int /* encoded_data_length */)
 
 // Sent when some data from a resource request has been downloaded to
 // file. This is only called in the 'download_to_file' case and replaces
 // ResourceMsg_DataReceived in the call sequence in that case.
 IPC_MESSAGE_CONTROL3(ResourceMsg_DataDownloaded,
                      int /* request_id */,
                      int /* data_len */,
@@ skipping 43 matching lines @@
 
 // Sent when the renderer process deletes a resource loader.
 IPC_MESSAGE_CONTROL1(ResourceHostMsg_ReleaseDownloadedFile,
                      int /* request_id */)
 
 // Sent by the renderer when a resource request changes priority.
 IPC_MESSAGE_CONTROL3(ResourceHostMsg_DidChangePriority,
                      int /* request_id */,
                      net::RequestPriority,
                      int /* intra_priority_value */)