Push API: add registration and error objects.

BUG=350378

Review URL: https://codereview.chromium.org/219163004

git-svn-id: svn://svn.chromium.org/blink/trunk@170778 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Show GPU memory limit on timline counters graph.

Review URL: https://codereview.chromium.org/219733003

git-svn-id: svn://svn.chromium.org/blink/trunk@170779 bbb929c8-8fbe-4397-9dbb-9b2b20218538