Revert r223961 and r224074 (using IO message loop instead of DEFAULT).

MessagePumpDefault was incorrectly using system time instead of monotonic time
for PostDelayedTask. This was fixed in r226378 so we don't need this workaround
any more.

BUG=293736

Review URL: https://codereview.chromium.org/25628004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226425 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed