Fix jscompile warning in Chromoting.

BUG=
R=jamiewalch@chromium.org

Review URL: https://codereview.chromium.org/157833002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249804 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249804
Use validating IPC enum macros in websocket messages

This is part of a long-running background task to remove the remaining
uses of the unchecked IPC_ENUM_TRAITS() macro.

BUG=246708

Review URL: https://codereview.chromium.org/157023003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249805 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249805