Remove PrefValueStore's dependency on PrefModelAssociator.

[email protected]
BUG=155525


Review URL: https://chromiumcodereview.appspot.com/11636018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@174680 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed