GitLab

This fixes the bug where you're able to click on the wrench of panels whose originating extension has been unloaded, resulting in a crash.

BUG=101118
TEST=PanelBrowserTest.NonExtensionDomainPanelsCloseOnUninstall


Review URL: http://codereview.chromium.org/8387010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@107837 0039d316-1c4b-4281-b951-d872f2087c98