ash: Rename LauncherModelObserver to ShelfModelObserver.

ash/launcher/launcher_item_delegate_manager.cc

Index: ash/launcher/launcher_item_delegate_manager.cc
diff --git a/ash/launcher/launcher_item_delegate_manager.cc b/ash/launcher/launcher_item_delegate_manager.cc
index e401b76bf318df2e8b586630d293a0ecb64c2053..ecc821cdbc5eeabdb73e688b36ae8c14dcc16070 100644
--- a/ash/launcher/launcher_item_delegate_manager.cc
+++ b/ash/launcher/launcher_item_delegate_manager.cc
@@ -44,24 +44,23 @@ LauncherItemDelegate* LauncherItemDelegateManager::GetLauncherItemDelegate(
   return NULL;
 }
 
-void LauncherItemDelegateManager::LauncherItemAdded(int index) {
+void LauncherItemDelegateManager::ShelfItemAdded(int index) {
 }
 
-void LauncherItemDelegateManager::LauncherItemRemoved(int index,
-                                                      ash::LauncherID id) {
+void LauncherItemDelegateManager::ShelfItemRemoved(int index, LauncherID id) {
   RemoveLauncherItemDelegate(id);
 }
 
-void LauncherItemDelegateManager::LauncherItemMoved(int start_index,
-                                                    int target_index) {
+void LauncherItemDelegateManager::ShelfItemMoved(int start_index,
+                                                 int target_index) {
 }
 
-void LauncherItemDelegateManager::LauncherItemChanged(
+void LauncherItemDelegateManager::ShelfItemChanged(
     int index,
     const LauncherItem& old_item) {
 }
 
-void LauncherItemDelegateManager::LauncherStatusChanged() {
+void LauncherItemDelegateManager::ShelfStatusChanged() {
 }
 
 void LauncherItemDelegateManager::RemoveLauncherItemDelegate(