bookmarks: Change BookmarkExpandedStateTracker to take PrefService.

chrome/browser/bookmarks/bookmark_expanded_state_tracker.h

Index: chrome/browser/bookmarks/bookmark_expanded_state_tracker.h
diff --git a/chrome/browser/bookmarks/bookmark_expanded_state_tracker.h b/chrome/browser/bookmarks/bookmark_expanded_state_tracker.h
index a254770bf3c1743cb88e27efc0d9c17ed6d24fe2..96ba77fa887de65c86e98843dfd5c2bfd599288b 100644
--- a/chrome/browser/bookmarks/bookmark_expanded_state_tracker.h
+++ b/chrome/browser/bookmarks/bookmark_expanded_state_tracker.h
@@ -9,12 +9,9 @@
 
 #include "chrome/browser/bookmarks/base_bookmark_model_observer.h"
 
-class BookmarkNode;
 class BookmarkModel;
-
-namespace content {
-class BrowserContext;
-}
+class BookmarkNode;
+class PrefService;
 
 // BookmarkExpandedStateTracker is used to track a set of expanded nodes. The
 // nodes are persisted in preferences. If an expanded node is removed from the
@@ -23,8 +20,8 @@ class BookmarkExpandedStateTracker : public BaseBookmarkModelObserver {
  public:
   typedef std::set<const BookmarkNode*> Nodes;
 
-  BookmarkExpandedStateTracker(content::BrowserContext* browser_context,
-                               BookmarkModel* bookmark_model);
+  BookmarkExpandedStateTracker(BookmarkModel* bookmark_model,
+                               PrefService* pref_service);
   virtual ~BookmarkExpandedStateTracker();
 
   // The set of expanded nodes.
@@ -42,12 +39,12 @@ class BookmarkExpandedStateTracker : public BaseBookmarkModelObserver {
                                    const BookmarkNode* node) OVERRIDE;
   virtual void BookmarkAllNodesRemoved(BookmarkModel* model) OVERRIDE;
 
-  // Resets the value in preferences from |expanded_nodes_|.
+  // Updates the value for |prefs::kBookmarkEditorExpandedNodes| from
+  // GetExpandedNodes().
   void UpdatePrefs(const Nodes& nodes);
 
-  content::BrowserContext* browser_context_;
-
   BookmarkModel* bookmark_model_;
+  PrefService* pref_service_;
 
   DISALLOW_COPY_AND_ASSIGN(BookmarkExpandedStateTracker);
 };