Move ManagePasswordsBubbleController knowledge out of PasswordManager.

This CL changes the flow between PasswordManager and PasswordManagerDelegate so
that PasswordManager is not directly responsible for showing the bubble. It
also renames the methods related to showing the password save infobar to be
more generic.

BUG=335116

Review URL: https://codereview.chromium.org/130443006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249395 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249395