adding new AEC dump start interface for chrome.

This is required because we are not allow to pass CRT objects across dll boundaries, that says, when we pass a file descriptor from chrome dll to libpeerconnection dll, the file descriptor will become invalid immediate, more information can be found here:
http://msdn.microsoft.com/en-us/library/ms235460.aspx

Chromium bug:crbug/415935
TEST=bots
R=bjornv@webrtc.org, kwiberg@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/28629004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7334 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_processing/include/audio_processing.h

@@ -14,6 +14,7 @@
 #include <stddef.h>  // size_t
 #include <stdio.h>  // FILE
 
+#include "webrtc/base/fileutils.h"
 #include "webrtc/common.h"
 #include "webrtc/typedefs.h"
 
@@ -325,6 +326,11 @@ class AudioProcessing {
   // of |handle| and closes it at StopDebugRecording().
   virtual int StartDebugRecording(FILE* handle) = 0;
 
+  // Same as above but uses an existing PlatformFile handle. Takes ownership
+  // of |handle| and closes it at StopDebugRecording().
+  // TODO(xians): Make this interface pure virtual.
+  virtual int StartDebugRecording(rtc::PlatformFile handle) { return -1; }
+
   // Stops recording debugging information, and closes the file. Recording
   // cannot be resumed in the same file (without overwriting it).
   virtual int StopDebugRecording() = 0;