components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/ui/gtk/browser_window_gtk.cc

Index: chrome/browser/ui/gtk/browser_window_gtk.cc
diff --git a/chrome/browser/ui/gtk/browser_window_gtk.cc b/chrome/browser/ui/gtk/browser_window_gtk.cc
index cdff82a275fc694f268f908326e670acac78167f..aee76203fced3bb036ce9a440993da4009f95c7d 100644
--- a/chrome/browser/ui/gtk/browser_window_gtk.cc
+++ b/chrome/browser/ui/gtk/browser_window_gtk.cc
@@ -1494,16 +1494,18 @@ GtkWidget* BrowserWindowGtk::titlebar_widget() const {
 }
 
 // static
-void BrowserWindowGtk::RegisterUserPrefs(PrefRegistrySyncable* registry) {
+void BrowserWindowGtk::RegisterUserPrefs(
+    user_prefs::PrefRegistrySyncable* registry) {
   bool custom_frame_default = false;
   // Avoid checking the window manager if we're not connected to an X server (as
   // is the case in Valgrind tests).
   if (ui::XDisplayExists())
     custom_frame_default = GetCustomFramePrefDefault();
 
-  registry->RegisterBooleanPref(prefs::kUseCustomChromeFrame,
-                                custom_frame_default,
-                                PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterBooleanPref(
+      prefs::kUseCustomChromeFrame,
+      custom_frame_default,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
 }
 
 WebContents* BrowserWindowGtk::GetDisplayedTab() {