GitLab

Design doc: https://bit.ly/2JgkZyc

This CL changes the intercept navigation throttle to avoid blocking
network requests from starting. Instead, policy decisions are computed
asynchronously, and the load is canceled+ignored at the next
NavigationThrottle callback.

Note that in cases where the request should be ignored, this wastes
some bytes. However, this is a pretty rare case. It looks like ~99% of
the time we won't cancel the navigation (from
Android.TabNavigationInterceptResult)

Bug: 793053
Change-Id: I9bf4eb29cf7ff92d31432eedb41cd446f738a492
Reviewed-on: https://chromium-review.googlesource.com/815354
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565764}