mash: Port mojo:ash_sysui's ContextMenuMus to mojo:ash.

ash/mus/bridge/wm_shell_mus.cc

Index: ash/mus/bridge/wm_shell_mus.cc
diff --git a/ash/mus/bridge/wm_shell_mus.cc b/ash/mus/bridge/wm_shell_mus.cc
index e2eb353e1b57e430b3afc5446e339fd99e6daf00..d39b65f9468abd34e8af7b72fde8e55357a4f89b 100644
--- a/ash/mus/bridge/wm_shell_mus.cc
+++ b/ash/mus/bridge/wm_shell_mus.cc
@@ -14,6 +14,7 @@
 #include "ash/common/shell_observer.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/system/tray/default_system_tray_delegate.h"
+#include "ash/common/wallpaper/wallpaper_delegate.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_event_handler.h"
 #include "ash/common/wm/maximize_mode/scoped_disable_internal_mouse_and_keyboard.h"
 #include "ash/common/wm/mru_window_tracker.h"
@@ -134,6 +135,9 @@ WmShellMus::WmShellMus(
 
   // TODO(jamescook): Port ash::sysui::KeyboardUIMus and use it here.
   SetKeyboardUI(KeyboardUI::Create());
+
+  // TODO(msw): Port WallpaperDelegateMus and support this (crbug.com/629605):
+  // wallpaper_delegate()->InitializeWallpaper();
 }
 
 WmShellMus::~WmShellMus() {
@@ -307,6 +311,7 @@ void WmShellMus::RecordTaskSwitchMetric(TaskSwitchSource source) {
 
 void WmShellMus::ShowContextMenu(const gfx::Point& location_in_screen,
                                  ui::MenuSourceType source_type) {
+  // TODO: http://crbug.com/640693.
   NOTIMPLEMENTED();
 }