Add support to invoke hangouts from people search.
This CL allows us to start a chat from people search (if the hangouts app is available and listening).

R=asargent@chromium.org, xiyuan@chromium.org
BUG=302805

Review URL: https://codereview.chromium.org/26048003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228600 0039d316-1c4b-4281-b951-d872f2087c98
Remove NOTIFICATION_WEB_CONTENTS_DESTROYED from AutoLoginRedirector.

BUG=170921
TEST=everything still works

Review URL: https://codereview.chromium.org/27019009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228601 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228601