Reland; WebWaitableEvent: drop an unnecessary 'virtual' from createWaitableEvent
Reland; WebWaitableEvent: drop an unnecessary 'virtual' from createWaitableEvent

Update from the last submission:
Nothing. Just wait for chromium update for html_viewer.

Original description:
As the last step to deprecate the old blink interface, drop an
unnecessary 'virtual' from createWaitableEvent.

BUG=507224
TEST=gn build with is_clang=true

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=198839

Review URL: https://codereview.chromium.org/1237033002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@198869 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk