GitLab

prerender: Add NavigationOrSwapObserver in browsertest.

Prerender browser tests are currently sensitive to prerenders occurring
synchronously. Already we require an ad-hoc content::RunMessageLoop() in
PrerenderPageNewTab because that one is asynchronous. Instead, introduce
a NavigationOrSwapObserver so NavigateToURL always waits for either the
swap or a normal navigation. This allows removing the
content::RunMessageLoop() call and is necessary for fixing beforeunload
handling.

Also split off DidDisplayPass and DidPrerenderPass into helper functions.

BUG=307592,304932
TEST=PrerenderBrowserTest.*

Review URL: https://codereview.chromium.org/102433010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243616 0039d316-1c4b-4281-b951-d872f2087c98