GitLab

- Refactor PartialScreenshotEventFiler so that it can be reused, and renamed it to OverlayEventFilter
- Use OverlayEventFilter for the keyboard overlay

BUG=129834
TEST=Manually check accelerators do not work when the keyboard overlay.


Review URL: https://chromiumcodereview.appspot.com/10825026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148504 0039d316-1c4b-4281-b951-d872f2087c98