Define rtc::BufferT, like rtc::Buffer but for any trivial type

webrtc/media/base/mediachannel.h

Index: webrtc/media/base/mediachannel.h
diff --git a/webrtc/media/base/mediachannel.h b/webrtc/media/base/mediachannel.h
index bd1185f7220154f950604fa0cbc12c3d724e0441..7c054b6f3a69b872f771f4301cb4628d376da1b1 100644
--- a/webrtc/media/base/mediachannel.h
+++ b/webrtc/media/base/mediachannel.h
@@ -17,6 +17,7 @@
 
 #include "webrtc/api/rtpparameters.h"
 #include "webrtc/base/basictypes.h"
+#include "webrtc/base/buffer.h"
 #include "webrtc/base/copyonwritebuffer.h"
 #include "webrtc/base/dscp.h"
 #include "webrtc/base/logging.h"
@@ -34,7 +35,6 @@
 #include "webrtc/pc/audiomonitor.h"
 
 namespace rtc {
-class Buffer;
 class RateLimiter;
 class Timing;
 }