[ChromeDriver] Began tracking Page.FrameStoppedLoading in Navigation Tracker

Sometimes Page.frameStoppedLoading fires without an associated
Page.loadEventFired. If this happens for the top frame, we assume
loading has finished.

R=johnchen@chromium.org

Bug: chromedriver:2809
Change-Id: Ie02ef9c7c374d29f29d4724fdaef9b48703b01c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1669239
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Julian Kung <juliankung@google.com>
Cr-Commit-Position: refs/heads/master@{#671071}
1 file changed