chromeos: Rename ash::WmShelf to Shelf

ash/shell/shell_delegate_impl.cc

Index: ash/shell/shell_delegate_impl.cc
diff --git a/ash/shell/shell_delegate_impl.cc b/ash/shell/shell_delegate_impl.cc
index dae311bd9c2ff19d88df1eb787391a751dc066a3..1a4a4eb8282afb9a30874a6c0612b543daa78ab1 100644
--- a/ash/shell/shell_delegate_impl.cc
+++ b/ash/shell/shell_delegate_impl.cc
@@ -149,9 +149,9 @@ std::unique_ptr<PaletteDelegate> ShellDelegateImpl::CreatePaletteDelegate() {
   return base::MakeUnique<PaletteDelegateImpl>();
 }
 
-ui::MenuModel* ShellDelegateImpl::CreateContextMenu(WmShelf* wm_shelf,
+ui::MenuModel* ShellDelegateImpl::CreateContextMenu(Shelf* shelf,
                                                     const ShelfItem* item) {
-  return new ContextMenu(wm_shelf);
+  return new ContextMenu(shelf);
 }
 
 GPUSupport* ShellDelegateImpl::CreateGPUSupport() {