Revert "Revert 249234 "Use MessagePumpDispatcher instead of MessageFilter""

This reverts commit 33c0f57d77e38a009034fb7d0e905755d9620035 with a trivial
modification to corp with a recent refactoring committed as r249105.

BUG=330735, 319122

Review URL: https://codereview.chromium.org/143503004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249650 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249650