MD Settings: clarify "controlled by" logic

chrome/common/extensions/api/settings_private.idl

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Use the <code>chrome.settingsPrivate</code> API to get or set preferences
 // from the settings UI.
 namespace settingsPrivate {
   // Type of a pref.
   enum PrefType { BOOLEAN, NUMBER, STRING, URL, LIST, DICTIONARY };
 
   // Source of a restricted pref, either by policy or other source.
   enum PolicySource {
     DEVICE_POLICY,
     USER_POLICY,
     OWNER,
     PRIMARY_USER,
+    // TODO(dbeam): This is kind of confusing. Extensions can be installed by
+    // users or force installed by a policy (https://goo.gl/f7L5aD). Maybe we
+    // could rename "PolicySource" to "ControlledBy" or "EnforcementSource"?

[stevenjb, 2016/11/09 18:03:30]

First off, I apologize for half completing this and not documenting it well (by
which I mean, at all).

It's been a while since I looked at this, but my head is at least partly in it
since I've been dealing with similar issues for the proxy configuration (which
is its own special hell).

There are a few approaches we could take here. One that comes to mind is to
rename this to EnforcementSource, rename PolicyEnforcement to EnforcementType
and include { POLICY_ENFORCED, POLICY_RECOMMENDED, EXTENSION_ENFORCED, NONE }.

Let's chat Wed and maybe put together a quick design / brainstorming doc.

     EXTENSION
   };
 
   // Enforcement type of a restricted pref.
   enum PolicyEnforcement { ENFORCED, RECOMMENDED };
 
   dictionary PrefObject {
     // The key for the pref.
     DOMString key;
 
@@ skipping 58 matching lines @@
         double zoom, optional SetDefaultZoomCallback callback);
   };
 
   interface Events {
     // Fired when a set of prefs has changed.
     //
     // |prefs| The prefs that changed.
     static void onPrefsChanged(PrefObject[] prefs);
   };
 };