Rename MediaHasVideo bit to MediaCanToggleControls.

Only set this bit for non-fullscreen video, since toggling is ignored for fullscreen video.

Chromium side change is https://codereview.chromium.org/201573013.

BUG=179489

Review URL: https://codereview.chromium.org/200723010

git-svn-id: svn://svn.chromium.org/blink/trunk@170701 bbb929c8-8fbe-4397-9dbb-9b2b20218538