MD Settings: add more extension controlled pref handling.

chrome/browser/extensions/api/settings_private/prefs_util.cc

Index: chrome/browser/extensions/api/settings_private/prefs_util.cc
diff --git a/chrome/browser/extensions/api/settings_private/prefs_util.cc b/chrome/browser/extensions/api/settings_private/prefs_util.cc
index e32baa11f46eac2beb28f262c0c407389ba09654..75083f20321e6eeba77a23b76be31dc30a504867 100644
--- a/chrome/browser/extensions/api/settings_private/prefs_util.cc
+++ b/chrome/browser/extensions/api/settings_private/prefs_util.cc
@@ -478,6 +478,7 @@ std::unique_ptr<settings_private::PrefObject> PrefsUtil::GetPref(
 #endif
 
   const Extension* extension = GetExtensionControllingPref(*pref_object);
+
   if (extension) {
     pref_object->controlled_by =
         settings_private::ControlledBy::CONTROLLED_BY_EXTENSION;
@@ -738,7 +739,12 @@ const Extension* PrefsUtil::GetExtensionControllingPref(
   if (pref_object.key == proxy_config::prefs::kProxy)
     return GetExtensionOverridingProxy(profile_);
 
-  return nullptr;
+  // If it's none of the above, attempt a more general strategy.
+  std::string extension_id =
+      ExtensionPrefValueMapFactory::GetForBrowserContext(profile_)
+          ->GetExtensionControllingPref(pref_object.key);

[Dan Beam, 2017/02/28 17:52:45]

if (extension_id.empty())
  return nullptr;

[scottchen, 2017/02/28 18:56:14]

Done.

+  return ExtensionRegistry::Get(profile_)->
+      GetExtensionById(extension_id, ExtensionRegistry::ENABLED);
 }
 
 }  // namespace extensions