Refactor AppListControllerDelegateCocoa so it has a ref to the service.

It keeps a pointer to AppListServiceMac which is used instead of getting
the global AppListServiceMac instance each time it is needed.

BUG=307837

Review URL: https://codereview.chromium.org/31813004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230122 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230122
Cleanup error handling in network handlers.

Also fixes two small bugs (missing returns after invoking the error callback) in ManagedNetworkConfigurationHandler.

BUG=NONE

Review URL: https://codereview.chromium.org/30593004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230123 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230123