Implement "pinned" mode in ash.

ash/wm/window_cycle_controller.cc

 // Copyright 2014 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/wm/window_cycle_controller.h"
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/wm/mru_window_tracker.h"
 #include "ash/common/wm_shell.h"
 #include "ash/metrics/user_metrics_recorder.h"
@@ skipping 56 matching lines @@
 }
 
 WindowCycleController::~WindowCycleController() {
 }
 
 // static
 bool WindowCycleController::CanCycle() {
   // Don't allow window cycling if the screen is locked or a modal dialog is
   // open.
   return !Shell::GetInstance()->session_state_delegate()->IsScreenLocked() &&
-         !WmShell::Get()->IsSystemModalWindowOpen();
+         !WmShell::Get()->IsSystemModalWindowOpen() &&
+         !WmShell::Get()->IsPinned();
 }
 
 void WindowCycleController::HandleCycleWindow(Direction direction) {
   if (!CanCycle())
     return;
 
   if (!IsCycling())
     StartCycling();
 
   Step(direction);
@@ skipping 34 matching lines @@
       active_window_before_window_cycle_ != active_window_after_window_cycle) {
     Shell::GetInstance()
         ->metrics()
         ->task_switch_metrics_recorder()
         .OnTaskSwitch(TaskSwitchMetricsRecorder::WINDOW_CYCLE_CONTROLLER);
   }
   active_window_before_window_cycle_ = nullptr;
 }
 
 }  // namespace ash