GitLab

This fixes a bug where overlays that don't push history entries still did when
closing them. Add a browser test to test this case.

BUG=379055
TEST=see bug

Review URL: https://codereview.chromium.org/306993006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274340 0039d316-1c4b-4281-b951-d872f2087c98