VP8: Making key frame interval a tunnable parameter

Review URL: https://webrtc-codereview.appspot.com/1070006

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3444 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/common_types.h b/common_types.h
index 492cb37..3c79137 100644
--- a/common_types.h
+++ b/common_types.h
@@ -530,6 +530,7 @@
     bool                 errorConcealmentOn;
     bool                 automaticResizeOn;
     bool                 frameDroppingOn;
+    int                  keyFrameInterval;
 };
 
 // Unknown specific