Mojo: Convert MessageInTransit* -> scoped_ptr<MessageInTransit>, part 1.

R=yzshen@chromium.org

Review URL: https://codereview.chromium.org/170013003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252607 0039d316-1c4b-4281-b951-d872f2087c98
Enable failing webgl conformance tests on mac gpu ati bots

It turns out they are all passing now.

BUG=308328
TEST=mac gpu ati bots
TBR=kbr@chromium.org

Review URL: https://codereview.chromium.org/167433005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252608 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252608