Revert 170483 - Remove PrefObserver usages, batch 12.

chrome/browser/ui/cocoa/browser_window_cocoa_unittest.mm

Index: chrome/browser/ui/cocoa/browser_window_cocoa_unittest.mm
===================================================================
--- chrome/browser/ui/cocoa/browser_window_cocoa_unittest.mm	(revision 170518)
+++ chrome/browser/ui/cocoa/browser_window_cocoa_unittest.mm	(working copy)
@@ -4,6 +4,7 @@
 
 #include "base/memory/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/prefs/public/pref_observer.h"
 #include "base/string_util.h"
 #include "chrome/browser/ui/bookmarks/bookmark_utils.h"
 #import "chrome/browser/ui/cocoa/browser_window_cocoa.h"
@@ -19,7 +20,7 @@
 // A BrowserWindowCocoa that goes PONG when
 // BOOKMARK_BAR_VISIBILITY_PREF_CHANGED is sent.  This is so we can be
 // sure we are observing it.
-class BrowserWindowCocoaPong : public BrowserWindowCocoa {
+class BrowserWindowCocoaPong : public BrowserWindowCocoa, public PrefObserver {
  public:
   BrowserWindowCocoaPong(Browser* browser,
                          BrowserWindowController* controller)
@@ -28,8 +29,10 @@
   }
   virtual ~BrowserWindowCocoaPong() { }
 
-  virtual void OnShowBookmarkBarChanged() OVERRIDE {
-    pong_ = true;
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE {
+    if (pref_name == prefs::kShowBookmarkBar)
+      pong_ = true;
   }
 
   bool pong_;