Add ability to change default pref values, and use in BrowserInstantController.

chrome/browser/profiles/profile_impl.cc

Index: chrome/browser/profiles/profile_impl.cc
diff --git a/chrome/browser/profiles/profile_impl.cc b/chrome/browser/profiles/profile_impl.cc
index e23498d65a24a68b0b9561a758af6a19a4974d5f..f3ae807b9538ecaa29638b5db68d9490840c91c3 100644
--- a/chrome/browser/profiles/profile_impl.cc
+++ b/chrome/browser/profiles/profile_impl.cc
@@ -388,6 +388,8 @@ ProfileImpl::ProfileImpl(
          create_mode == CREATE_MODE_SYNCHRONOUS);
   bool async_prefs = create_mode == CREATE_MODE_ASYNCHRONOUS;
 
+  chrome::RegisterUserPrefs(pref_registry_);
+
   {
     // On startup, preference loading is always synchronous so a scoped timer
     // will work here.
@@ -707,10 +709,6 @@ void ProfileImpl::OnPrefsLoaded(bool success) {
     return;
   }
 
-  // TODO(joi): Registration can move to the constructor once it
-  // doesn't need the PrefService parameter.
-  chrome::RegisterUserPrefs(prefs_.get(), pref_registry_);
-
   // TODO(mirandac): remove migration code after 6 months (crbug.com/69995).
   if (g_browser_process->local_state())
     chrome::MigrateBrowserPrefs(this, g_browser_process->local_state());