Let chrome_prefs handle Preferences initialization from master_preferences.

chrome/browser/profiles/profile_impl.h

Index: chrome/browser/profiles/profile_impl.h
diff --git a/chrome/browser/profiles/profile_impl.h b/chrome/browser/profiles/profile_impl.h
index 9751628547e7f78b4eb3c7ef1ba7c1ec769ece44..f56bba8e25b3e086fbeb0f69b2cc3c2e2e0ad88a 100644
--- a/chrome/browser/profiles/profile_impl.h
+++ b/chrome/browser/profiles/profile_impl.h
@@ -69,6 +69,12 @@ class ProfileImpl : public Profile {
   // |profile_path|.
   static void ResetPrefHashStore(const base::FilePath& profile_path);
 
+  // Initializes the preferences for the profile at |profile_path| with the
+  // preference values in |master_prefs|. Returns true on success.
+  static bool InitializePrefsFromMasterPrefs(
+      const base::FilePath& profile_path,
+      const base::DictionaryValue& master_prefs);
+
   // content::BrowserContext implementation:
   virtual base::FilePath GetPath() const OVERRIDE;
   virtual content::DownloadManagerDelegate*