Use the native frame for the task manager on Linux Aura

ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
index 1ecd9962e7901ac5290c861b11afa46c719d50ae..1882594e052143d885537aef013f7ecc270f0931 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
@@ -35,7 +35,6 @@
 #include "ui/views/widget/widget_hwnd_utils.h"
 #include "ui/views/win/fullscreen_handler.h"
 #include "ui/views/win/hwnd_message_handler.h"
-#include "ui/views/window/native_frame_view.h"
 #include "ui/wm/core/compound_event_filter.h"
 #include "ui/wm/core/input_method_event_filter.h"
 #include "ui/wm/core/window_animations.h"
@@ -382,11 +381,6 @@ void DesktopWindowTreeHostWin::FrameTypeChanged() {
   SetWindowTransparency();
 }
 
-NonClientFrameView* DesktopWindowTreeHostWin::CreateNonClientFrameView() {
-  return GetWidget()->ShouldUseNativeFrame() ?
-      new NativeFrameView(GetWidget()) : NULL;
-}
-
 void DesktopWindowTreeHostWin::SetFullscreen(bool fullscreen) {
   message_handler_->fullscreen_handler()->SetFullscreen(fullscreen);
   // TODO(sky): workaround for ScopedFullscreenVisibility showing window