Improve session restore performance.

Session restoration completion code was moved from
didCommitNavigation to didStartProvisionalNavigation.
This change will allow the user to start interacting with
web contents without waiting until the first post-restore
navigation is complete.

There will be no committed URL until the first post-restore
navigation is complete, but user should be able to load new
pages and perform back forward navigations.

Bug: 877671
Change-Id: Iceeeff857aee36bf4151f247815c0705ac377e73
Commit-Queue: Eugene But <>
Auto-Submit: Eugene But <>
Reviewed-by: Danyao Wang <>
Cr-Commit-Position: refs/heads/master@{#625400}
10 files changed