Add network_handler_callbacks.cc

This does some cleanup to allow NetworkStateHandler to use the same error callback infrastructure as NetworkConfigurationHandler.
It also adds event logging for errors.

BUG=none

Review URL: https://codereview.chromium.org/11416149

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@169475 0039d316-1c4b-4281-b951-d872f2087c98
10 files changed