Remove usage of WebContentsTester::SimulateNavigationStart

This CL removes usage of WebContentsTester::SimulateNavigationStart in
favor of using NavigationSimulator. Following this CL,
WebContentsTester::SimulateNavigationStart is no longer part of the
content/ public interface. This CL also removes the last two usages of
RenderFrameHostTester::SimulateNavigationError and
SimulateNavigationErrorPageCommit outside of content/. Hence, those
functions are also removed from the public interface.

BUG=728571

Change-Id: I2b14b1f24543476c289461d2e6b2b3ecf4667ec9
Reviewed-on: https://chromium-review.googlesource.com/621566
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Nathan Parker <nparker@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#496677}
14 files changed