components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/extensions/extension_prefs_unittest.h

Index: chrome/browser/extensions/extension_prefs_unittest.h
diff --git a/chrome/browser/extensions/extension_prefs_unittest.h b/chrome/browser/extensions/extension_prefs_unittest.h
index 86b622bffe85993b2dc1291822efd56f3c5c9ee2..2bc227b8a2c1eb07331bcc06e6c2109a5389bf7f 100644
--- a/chrome/browser/extensions/extension_prefs_unittest.h
+++ b/chrome/browser/extensions/extension_prefs_unittest.h
@@ -11,12 +11,14 @@
 #include "content/public/test/test_browser_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-class PrefRegistrySyncable;
-
 namespace base {
 class Value;
 }
 
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 namespace extensions {
 class Extension;
 
@@ -36,7 +38,7 @@ class ExtensionPrefsTest : public ExtensionTest {
   virtual void Verify() = 0;
 
   // This function is called to Register preference default values.
-  virtual void RegisterPreferences(PrefRegistrySyncable* registry);
+  virtual void RegisterPreferences(user_prefs::PrefRegistrySyncable* registry);
 
   virtual void SetUp() OVERRIDE;
 
@@ -59,7 +61,8 @@ class ExtensionPrefsPrepopulatedTest : public ExtensionPrefsTest {
   ExtensionPrefsPrepopulatedTest();
   virtual ~ExtensionPrefsPrepopulatedTest();
 
-  virtual void RegisterPreferences(PrefRegistrySyncable* registry) OVERRIDE;
+  virtual void RegisterPreferences(
+      user_prefs::PrefRegistrySyncable* registry) OVERRIDE;
 
   void InstallExtControlledPref(Extension* ext,
                                 const std::string& key,