Eliminate ash::Shell access in ShelfView

ash/aura/wm_shell_aura.cc

 // Copyright 2016 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 "ash/aura/wm_shell_aura.h"
 
 #include <utility>
 
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/session/session_state_delegate.h"
@@ skipping 123 matching lines @@
 
 void WmShellAura::RecordUserMetricsAction(UserMetricsAction action) {
   Shell::GetInstance()->metrics()->RecordUserMetricsAction(action);
 }
 
 void WmShellAura::RecordTaskSwitchMetric(TaskSwitchSource source) {
   Shell::GetInstance()->metrics()->task_switch_metrics_recorder().OnTaskSwitch(
       source);
 }
 
+void WmShellAura::ShowContextMenu(const gfx::Point& location_in_screen,
+                                  ui::MenuSourceType source_type) {
+  Shell::GetInstance()->ShowContextMenu(location_in_screen, source_type);
+}
+
 std::unique_ptr<WindowResizer> WmShellAura::CreateDragWindowResizer(
     std::unique_ptr<WindowResizer> next_window_resizer,
     wm::WindowState* window_state) {
   return base::WrapUnique(
       DragWindowResizer::Create(next_window_resizer.release(), window_state));
 }
 
 std::unique_ptr<WindowCycleEventFilter>
 WmShellAura::CreateWindowCycleEventFilter() {
   return base::MakeUnique<WindowCycleEventFilterAura>();
@@ skipping 88 matching lines @@
   FOR_EACH_OBSERVER(WmDisplayObserver, display_observers_,
                     OnDisplayConfigurationChanging());
 }
 
 void WmShellAura::OnDisplayConfigurationChanged() {
   FOR_EACH_OBSERVER(WmDisplayObserver, display_observers_,
                     OnDisplayConfigurationChanged());
 }
 
 }  // namespace ash