Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
@@ skipping 962 matching lines @@
     gtk_widget_modify_bg(paint_box_, GTK_STATE_NORMAL, &paint_box_color);
 
     if (bookmark_bar_state_ == BookmarkBar::DETACHED) {
       GdkColor stroke_color = theme_service_->UsingNativeTheme() ?
           theme_service_->GetBorderColor() :
           theme_service_->GetGdkColor(ThemeService::COLOR_NTP_HEADER);
       gtk_util::SetRoundedWindowBorderColor(paint_box_, stroke_color);
     }
 
     SetOverflowButtonAppearance();
-  } else if (type == chrome::NOTIFICATION_PREF_CHANGED) {
-    const std::string& pref_name =
-        *content::Details<std::string>(details).ptr();
-    if (pref_name == prefs::kEditBookmarksEnabled)
-      OnEditBookmarksEnabledChanged();
   }
 }
 
+void BookmarkBarGtk::OnPreferenceChanged(PrefServiceBase* service,
+                                         const std::string& pref_name) {
+  if (pref_name == prefs::kEditBookmarksEnabled)
+    OnEditBookmarksEnabledChanged();
+}
+
 GtkWidget* BookmarkBarGtk::CreateBookmarkButton(const BookmarkNode* node) {
   GtkWidget* button = theme_service_->BuildChromeButton();
   bookmark_utils::ConfigureButtonForNode(node, model_, button, theme_service_);
 
   // The tool item is also a source for dragging
   gtk_drag_source_set(button, GDK_BUTTON1_MASK, NULL, 0,
       static_cast<GdkDragAction>(GDK_ACTION_MOVE | GDK_ACTION_COPY));
   int target_mask = bookmark_utils::GetCodeMask(node->is_folder());
   ui::SetSourceTargetListFromCodeMask(button, target_mask);
   g_signal_connect(button, "drag-begin",
@@ skipping 456 matching lines @@
 void BookmarkBarGtk::OnEditBookmarksEnabledChanged() {
   GtkDestDefaults dest_defaults =
       *edit_bookmarks_enabled_ ? GTK_DEST_DEFAULT_ALL :
                                  GTK_DEST_DEFAULT_DROP;
   gtk_drag_dest_set(overflow_button_, dest_defaults, NULL, 0, kDragAction);
   gtk_drag_dest_set(other_bookmarks_button_, dest_defaults,
                     NULL, 0, kDragAction);
   ui::SetDestTargetList(overflow_button_, kDestTargetList);
   ui::SetDestTargetList(other_bookmarks_button_, kDestTargetList);
 }