Mark all virtual overrides in the hierarchies of RtpDump and
VCMPacketizationCallback as such.

This will make further changes to these classes safer by ensuring that the
compile breaks if the base class changes and not all overrides are fixed.

This also marks all other such overrides in the affected files.

BUG=none
TEST=none
R=henrike@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/19319004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7161 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/utility/source/video_coder.h b/webrtc/modules/utility/source/video_coder.h
index 8e4344b..03aa511 100644
--- a/webrtc/modules/utility/source/video_coder.h
+++ b/webrtc/modules/utility/source/video_coder.h
@@ -43,11 +43,11 @@
 private:
     // VCMReceiveCallback function.
     // Note: called by VideoCodingModule when decoding finished.
-    int32_t FrameToRender(I420VideoFrame& videoFrame);
+    virtual int32_t FrameToRender(I420VideoFrame& videoFrame) OVERRIDE;
 
     // VCMPacketizationCallback function.
     // Note: called by VideoCodingModule when encoding finished.
-    int32_t SendData(
+    virtual int32_t SendData(
         FrameType /*frameType*/,
         uint8_t /*payloadType*/,
         uint32_t /*timeStamp*/,
@@ -55,7 +55,7 @@
         const uint8_t* payloadData,
         uint32_t payloadSize,
         const RTPFragmentationHeader& /* fragmentationHeader*/,
-        const RTPVideoHeader* rtpTypeHdr);
+        const RTPVideoHeader* rtpTypeHdr) OVERRIDE;
 
     VideoCodingModule* _vcm;
     I420VideoFrame* _decodedVideo;