Adds ActivityLog attributes to mouse and keyboard events

The test CL for this code is in Chromium: see Issue 19540019.

BUG=260336
R=felt@chromium.org

Review URL: https://chromiumcodereview.appspot.com/19697008

git-svn-id: svn://svn.chromium.org/blink/trunk@154552 bbb929c8-8fbe-4397-9dbb-9b2b20218538