Don't show status bar updates from originating renderer when fullscreen

In fullscreen mode WebContents has two renderviews. One for the
fullscreen display, and one for the originating page. It's entirely
possible that the renderer from the originating page tries to update
the status bar url. This seems to mostly occur because we can delay mouse
events so that when transitioning to fullscreen we can end up sending
a mouse event to the originating renderer after we're fullscreen,
which can result in the originating page trying to update the target
url of the status bar.

When fullscreen we should only care about updates from the fullscreen
renderer.

[email protected]
BUG=380005
TEST=see bug

Review URL: https://codereview.chromium.org/811523005

Cr-Commit-Position: refs/heads/master@{#310915}
6 files changed