bookmarks: Add HasBookmarks() method to BookmarkModel API.

chrome/browser/bookmarks/bookmark_model.h

Index: chrome/browser/bookmarks/bookmark_model.h
diff --git a/chrome/browser/bookmarks/bookmark_model.h b/chrome/browser/bookmarks/bookmark_model.h
index 63d12adac28d2d6a1d3aa41b5ffbe212a71969e2..5ea807589ac1225a053965557a1248b75edaea0c 100644
--- a/chrome/browser/bookmarks/bookmark_model.h
+++ b/chrome/browser/bookmarks/bookmark_model.h
@@ -253,6 +253,10 @@ class BookmarkModel : public NotificationObserver, public BookmarkService {
   // Returns all the bookmarked urls. This method is thread safe.
   virtual void GetBookmarks(std::vector<GURL>* urls);
 
+  // Returns true if there are bookmarks, otherwise returns false. This method
+  // is thread safe.
+  bool HasBookmarks();
+
   // Returns true if there is a bookmark for the specified URL. This method is
   // thread safe. See BookmarkService for more details on this.
   virtual bool IsBookmarked(const GURL& url);