Update heuristic to consider the UserGestureIndicator to invoke on-screen
keyboard on a programmatic focus() call.

Design doc: https://docs.google.com/document/d/1GxvXrLODE3p3RD1p8cZRrtb59zqRc8B2SnZMiu_V510/edit?usp=sharing

BUG=371927

Review URL: https://codereview.chromium.org/276033002

git-svn-id: svn://svn.chromium.org/blink/trunk@176585 bbb929c8-8fbe-4397-9dbb-9b2b20218538