Use validating param traits for MediaStreamType enum

BUG=249854

Review URL: https://chromiumcodereview.appspot.com/17253003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@208055 0039d316-1c4b-4281-b951-d872f2087c98

content/common/media/media_stream_messages.h

@@ -16,7 +16,8 @@
 #define IPC_MESSAGE_EXPORT CONTENT_EXPORT
 #define IPC_MESSAGE_START MediaStreamMsgStart
 
-IPC_ENUM_TRAITS(content::MediaStreamType)
+IPC_ENUM_TRAITS_MAX_VALUE(content::MediaStreamType,
+                          content::NUM_MEDIA_TYPES - 1)
 
 IPC_STRUCT_TRAITS_BEGIN(content::StreamOptions)
   IPC_STRUCT_TRAITS_MEMBER(audio_type)