TrackedPreferences are initialized when a profile is created or loaded. But profiles that have not been loaded are not being tracked.

At startup, identify profiles whose PrefHashStores have not been initialized and initialize them.

BUG=336478

Review URL: https://codereview.chromium.org/117593002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247250 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247250
Add locking control to user flows, disallow screen locking during user creation.

BUG=332756

Review URL: https://codereview.chromium.org/136003006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247251 0039d316-1c4b-4281-b951-d872f2087c98
Restart plugin loading only if the plugin list has actually become stale.

BUG=171404

Review URL: https://codereview.chromium.org/128773002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247252 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247252