Following the decision to launch PlzNavigate on M60, this CL enables
PlzNavigate on trunk by default. It also transforms the
browser_side_navigation* test suites (that used to test PlzNavigate) in
renderer_side_navigation* versions that we will use to test the old
navigation codepath until we deem that it is safe enough to remove it.

BUG=689549

Change-Id: I4fe9a56cc98617b9b470800d63c56f330bb3b87a
Reviewed-on: https://chromium-review.googlesource.com/581488


Commit-Queue: Camille Lamy <clamy@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#502251}