Introduce //components/user_prefs, use to eliminate c/b/prefs dependency in Autofill.

chrome/browser/ui/browser_instant_controller.cc

Index: chrome/browser/ui/browser_instant_controller.cc
diff --git a/chrome/browser/ui/browser_instant_controller.cc b/chrome/browser/ui/browser_instant_controller.cc
index 5a15dc9b350b016f03341c04eb26e8c50480815f..93bef6f4bc99c31adbaed69d5c0a547b85b4eaab 100644
--- a/chrome/browser/ui/browser_instant_controller.cc
+++ b/chrome/browser/ui/browser_instant_controller.cc
@@ -6,7 +6,6 @@
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/extensions/extension_service.h"
-#include "chrome/browser/prefs/pref_registry_syncable.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/themes/theme_properties.h"
 #include "chrome/browser/themes/theme_service.h"
@@ -23,6 +22,7 @@
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
+#include "components/user_prefs/pref_registry_syncable.h"
 #include "content/public/browser/notification_service.h"
 #include "grit/theme_resources.h"
 #include "ui/gfx/color_utils.h"