Ignore ManagedState changes to existing state.

Changing state to an existing state is a no-op that produces event log 
noise and extra callbacks.

BUG=239652

Review URL: https://chromiumcodereview.appspot.com/15132004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@200229 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed