bookmarks: Move BookmarkModelObserver into 'bookmarks' namespace.

components/bookmarks/browser/bookmark_model.h

Index: components/bookmarks/browser/bookmark_model.h
diff --git a/components/bookmarks/browser/bookmark_model.h b/components/bookmarks/browser/bookmark_model.h
index 1388e5bfc268dc4ded2bd7dc6d31117416890eaf..b72d396abcbb0c669875988a283fc5c62ee3b0dd 100644
--- a/components/bookmarks/browser/bookmark_model.h
+++ b/components/bookmarks/browser/bookmark_model.h
@@ -23,7 +23,6 @@
 #include "ui/gfx/image/image.h"
 #include "url/gurl.h"
 
-class BookmarkModelObserver;
 class PrefService;
 
 namespace base {
@@ -36,6 +35,7 @@ class BookmarkCodecTest;
 class BookmarkExpandedStateTracker;
 class BookmarkIndex;
 class BookmarkLoadDetails;
+class BookmarkModelObserver;
 class BookmarkStorage;
 class ScopedGroupBookmarkActions;
 class TestBookmarkClient;
@@ -112,8 +112,8 @@ class BookmarkModel : public KeyedService {
   // (as long as the model is loaded).
   const BookmarkNode* GetParentForNewNodes();
 
-  void AddObserver(BookmarkModelObserver* observer);
-  void RemoveObserver(BookmarkModelObserver* observer);
+  void AddObserver(bookmarks::BookmarkModelObserver* observer);
+  void RemoveObserver(bookmarks::BookmarkModelObserver* observer);
 
   // Notifies the observers that an extensive set of changes is about to happen,
   // such as during import or sync, so they can delay any expensive UI updates
@@ -417,7 +417,7 @@ class BookmarkModel : public KeyedService {
   int64 next_node_id_;
 
   // The observers.
-  ObserverList<BookmarkModelObserver> observers_;
+  ObserverList<bookmarks::BookmarkModelObserver> observers_;
 
   // Set of nodes ordered by URL. This is not a map to avoid copying the
   // urls.