Notify RendererScheduler of starting LOADING phase on OnCommitNavigation

Blink Scheduler has been considering that the renderer is in the loading
phase after OnNavigate or DidCommitProvisionalLoad event. However on the
PlzNavigate case, OnNavigate doesn't happen and DidCommitProvisionalLoad
happens after the main resource load, so the renderer is not in the loading
phase while a main resource request is in-flight. That may cause a throttled
loading task queue, and delay the main resource load.

This CL adds OnCommitNavigation as a trigger of the loading phase,
so that the main resource is always loaded in an unthrottled task queue.

Bug: 732738
Change-Id: I3a9d14d8bb6ec35f9cb56b5dc567afa8f65f2e87
Reviewed-on: https://chromium-review.googlesource.com/542717
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#482161}
1 file changed