Profile shouldn't own background page stuff.

BackgroundContentsService and BackgroundModeManager now have factories
which own them, using Profile as a key. This uses the
ProfileKeyedService infrastructure.

BUG=77155
TEST=existing tests


Review URL: http://codereview.chromium.org/6831016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@81723 0039d316-1c4b-4281-b951-d872f2087c98
19 files changed