Remove deprecated AudioCodingModule::Destroy.

Have Channel hold a pointer rather than reference, and shorten the name.

TESTED=trybots
R=turaj@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2256004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4820 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/utility/source/coder.h

@@ -13,6 +13,7 @@
 
 #include "webrtc/common_types.h"
 #include "webrtc/modules/audio_coding/main/interface/audio_coding_module.h"
+#include "webrtc/system_wrappers/interface/scoped_ptr.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
@@ -49,7 +50,7 @@ protected:
                              const RTPFragmentationHeader* fragmentation);
 
 private:
-    AudioCodingModule* _acm;
+    scoped_ptr<AudioCodingModule> _acm;
 
     CodecInst _receiveCodec;