Use IO loop for the compositor thread in the renderer on posix.

MessagePumpDefault breaks PostDelayedTask on posix because it uses system time.
MessagePumpIO uses monotonic time, so is immune to these problems.

(These threads because they schedule things with PostDelayedTask).

BUG=293736

Review URL: https://chromiumcodereview.appspot.com/24234002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224074 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed