Make CrOS proxy configuration write prefs directly.

chrome/browser/net/pref_proxy_config_service.h

Index: chrome/browser/net/pref_proxy_config_service.h
diff --git a/chrome/browser/net/pref_proxy_config_service.h b/chrome/browser/net/pref_proxy_config_service.h
index 661a250733ac89761e916a7a0448bf1712b2edca..b5782b05321768ea3e0a4b8b5488e218f6320ce7 100644
--- a/chrome/browser/net/pref_proxy_config_service.h
+++ b/chrome/browser/net/pref_proxy_config_service.h
@@ -32,7 +32,14 @@ class PrefProxyConfigTracker
     virtual void OnPrefProxyConfigChanged() = 0;
   };
 
-  explicit PrefProxyConfigTracker(PrefService* pref_service);
+  // Initialize a tracker that will retrieve the configuration from
+  // |pref_service|. |fallback_pref_service| may be NULL. If specfied, it is
+  // consulted for a user pref (and only that!) if the user preference is
+  // missing in the main |pref_service|. This allows us to default the user
+  // preference to the |local_state| preference if there is no user preference
+  // for the profile.
+  PrefProxyConfigTracker(PrefService* pref_service,
+                         PrefService* fallback_pref_service);
   virtual ~PrefProxyConfigTracker();
 
   // Observer manipulation is only valid on the IO thread.
@@ -81,6 +88,11 @@ class PrefProxyConfigTracker
   PrefService* pref_service_;
   scoped_ptr<PrefSetObserver> proxy_prefs_observer_;
 
+  // A fallback PrefSerice that is checked for user preferences if
+  // |pref_service| doesn't have any user preference.
+  PrefService* fallback_pref_service_;
+  scoped_ptr<PrefSetObserver> fallback_proxy_prefs_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(PrefProxyConfigTracker);
 };