GitLab

(original change: https://codereview.chromium.org/2042763002)

In layout tests when preferences were being overridden by specific tests they
were not being properly applied in the browser. The WebPreferences cached by the
RenderViewHost was not updated and so they would not effect the existing window.
This fixes that and changes the way spatial navigation is enabled in layout
tests to adapt to this change.

The problem the original change that caused it to be reverted was that it made
preferences leak between tests when the Shell window was reused. This version
fixes that by storing a clean copy of the test-ready WebPrecerences created with
a brand new RenderView and using that to reset existing windows' preferences.

This is an spin off change to support the moving of mixed content checks to
the browser, which requires the browser to be immediately effected by
preferences updates.

BUG=576270, 620126

Review-Url: https://codereview.chromium.org/2134723002
Cr-Commit-Position: refs/heads/master@{#404627}