Replace content::NavigationState public interface with some bools

Instead of exposing NavigationState, observers get two additional
values in Did{Start,Commit}ProvisionalLoad callbacks.

This will allow us to remove NavigationState entirely to simplify
navigation tracking between blink and content. As a first step,
we can stop tracking transition type.

TBR=boliu@chromium.org,thakis@chromium.org,rockot@chromium.org,blundell@chromium.org

Bug: 855189
Change-Id: I6344ca4716121af9513c9bc672e5e9b28d49f055
Reviewed-on: https://chromium-review.googlesource.com/1226198
Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592204}
48 files changed