FrameLoader: move CancelParsing and CheckCompleted earlier

This way we do it before creating new provisional loader, which
will help in the future when there would be no provisional loader.

Added Document::Abort method which encapsulates CancelParsing
and CheckCompleted and also does not issue undesired DidFinishNavigation.

Bug: 831155
Change-Id: Ica5d968508d7aed7bb07125702ceeaeb6f389497
Reviewed-on: https://chromium-review.googlesource.com/1119262
Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574650}
5 files changed