Separated alt-tab window cycle from overview mode

This change separates the logic into two different classes. It also
- Brings back a bounce animation when there is only one window that was
lost at some point in the past.
- Removes the minimized animation if there is only one window while alt tabbing.

Basically I brought back from the past two classes,
WindowCycleController and WindowCycleList and adapted them
to work with the new codebase. Also, I moved some tests from
WindowSelectorUnittest to WindowCycleControllerUnittest, and 
removed the ones that are now irrelevant. 

Finally, we are also dropping support for alt-tabbing while
in overview mode in favour of cancelling the latter.
BUG=365786
TEST=none

Review URL: https://codereview.chromium.org/260883005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269997 0039d316-1c4b-4281-b951-d872f2087c98

ash/accelerators/accelerator_controller.cc

@@ -49,6 +49,7 @@
 #include "ash/wm/overview/window_selector_controller.h"
 #include "ash/wm/partial_screenshot_view.h"
 #include "ash/wm/power_button_controller.h"
+#include "ash/wm/window_cycle_controller.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
 #include "ash/wm/wm_event.h"
@@ -127,8 +128,8 @@ bool HandleCycleBackwardMRU(const ui::Accelerator& accelerator) {
   if (accelerator.key_code() == ui::VKEY_TAB)
     base::RecordAction(base::UserMetricsAction("Accel_PrevWindow_Tab"));
 
-  Shell::GetInstance()->window_selector_controller()->HandleCycleWindow(
-      WindowSelector::BACKWARD);
+  Shell::GetInstance()->window_cycle_controller()->HandleCycleWindow(
+      WindowCycleController::BACKWARD);
   return true;
 }
 
@@ -136,8 +137,8 @@ bool HandleCycleForwardMRU(const ui::Accelerator& accelerator) {
   if (accelerator.key_code() == ui::VKEY_TAB)
     base::RecordAction(base::UserMetricsAction("Accel_NextWindow_Tab"));
 
-  Shell::GetInstance()->window_selector_controller()->HandleCycleWindow(
-      WindowSelector::FORWARD);
+  Shell::GetInstance()->window_cycle_controller()->HandleCycleWindow(
+      WindowCycleController::FORWARD);
   return true;
 }
 

ash/accelerators/accelerator_controller_unittest.cc

@@ -1199,7 +1199,7 @@ TEST_F(AcceleratorControllerTest, DisallowedWithNoWindow) {
   for (size_t i = 0; i < kActionsNeedingWindowLength; ++i) {
     delegate->TriggerAccessibilityAlert(A11Y_ALERT_NONE);
     GetController()->PerformAction(kActionsNeedingWindow[i], dummy);
-    EXPECT_EQ(delegate->GetLastAccessibilityAlert(), A11Y_ALERT_NONE);
+    EXPECT_NE(delegate->GetLastAccessibilityAlert(), A11Y_ALERT_WINDOW_NEEDED);
   }
 
   // Don't alert if we have a minimized window either.
@@ -1207,7 +1207,7 @@ TEST_F(AcceleratorControllerTest, DisallowedWithNoWindow) {
   for (size_t i = 0; i < kActionsNeedingWindowLength; ++i) {
     delegate->TriggerAccessibilityAlert(A11Y_ALERT_NONE);
     GetController()->PerformAction(kActionsNeedingWindow[i], dummy);
-    EXPECT_EQ(delegate->GetLastAccessibilityAlert(), A11Y_ALERT_NONE);
+    EXPECT_NE(delegate->GetLastAccessibilityAlert(), A11Y_ALERT_WINDOW_NEEDED);
   }
 }
 

ash/ash.gyp

@@ -590,6 +590,10 @@
         'wm/overview/window_overview.h',
         'wm/overview/window_selector.cc',
         'wm/overview/window_selector.h',
+        'wm/window_cycle_controller.cc',
+        'wm/window_cycle_controller.h',
+        'wm/window_cycle_list.cc',
+        'wm/window_cycle_list.h',
         'wm/overview/window_selector_controller.cc',
         'wm/overview/window_selector_controller.h',
         'wm/overview/window_selector_delegate.h',
@@ -998,6 +1002,7 @@
         'wm/toplevel_window_event_handler_unittest.cc',
         'wm/video_detector_unittest.cc',
         'wm/window_animations_unittest.cc',
+        'wm/window_cycle_controller_unittest.cc',
         'wm/window_manager_unittest.cc',
         'wm/window_modality_controller_unittest.cc',
         'wm/window_positioner_unittest.cc',

ash/shell.cc

@@ -73,6 +73,7 @@
 #include "ash/wm/toplevel_window_event_handler.h"
 #include "ash/wm/video_detector.h"
 #include "ash/wm/window_animations.h"
+#include "ash/wm/window_cycle_controller.h"
 #include "ash/wm/window_positioner.h"
 #include "ash/wm/window_properties.h"
 #include "ash/wm/window_util.h"
@@ -712,6 +713,7 @@ Shell::~Shell() {
   shadow_controller_.reset();
   resize_shadow_controller_.reset();
 
+  window_cycle_controller_.reset();
   window_selector_controller_.reset();
   mru_window_tracker_.reset();
 
@@ -946,6 +948,7 @@ void Shell::Init() {
   high_contrast_controller_.reset(new HighContrastController);
   video_detector_.reset(new VideoDetector);
   window_selector_controller_.reset(new WindowSelectorController());
+  window_cycle_controller_.reset(new WindowCycleController());
 
   tooltip_controller_.reset(
       new views::corewm::TooltipController(

ash/shell.h

@@ -363,6 +363,9 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   VideoDetector* video_detector() {
     return video_detector_.get();
   }
+  WindowCycleController* window_cycle_controller() {
+    return window_cycle_controller_.get();
+  }
   WindowSelectorController* window_selector_controller() {
     return window_selector_controller_.get();
   }
@@ -644,6 +647,7 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   scoped_ptr<MruWindowTracker> mru_window_tracker_;
   scoped_ptr< ::wm::UserActivityDetector> user_activity_detector_;
   scoped_ptr<VideoDetector> video_detector_;
+  scoped_ptr<WindowCycleController> window_cycle_controller_;
   scoped_ptr<WindowSelectorController> window_selector_controller_;
   scoped_ptr<FocusCycler> focus_cycler_;
   scoped_ptr<DisplayController> display_controller_;

ash/wm/overview/window_overview.cc

@@ -120,12 +120,10 @@ void CleanupWidgetAfterAnimationObserver::OnLayerAnimationScheduled(
 }  // namespace
 
 WindowOverview::WindowOverview(WindowSelector* window_selector,
-                               WindowSelectorItemList* windows,
-                               aura::Window* single_root_window)
+                               WindowSelectorItemList* windows)
     : window_selector_(window_selector),
       windows_(windows),
       selection_index_(0),
-      single_root_window_(single_root_window),
       overview_start_time_(base::Time::Now()),
       cursor_client_(NULL) {
   Shell* shell = Shell::GetInstance();
@@ -151,11 +149,9 @@ WindowOverview::WindowOverview(WindowSelector* window_selector,
   shell->GetScreen()->AddObserver(this);
   shell->metrics()->RecordUserMetricsAction(UMA_WINDOW_OVERVIEW);
   HideAndTrackNonOverviewWindows();
-  // Send an a11y alert only if the overview was activated by the user.
-  if (window_selector_->mode() == WindowSelector::OVERVIEW) {
-    shell->accessibility_delegate()->TriggerAccessibilityAlert(
-        A11Y_ALERT_WINDOW_OVERVIEW_MODE_ENTERED);
-  }
+  // Send an a11y alert.
+  shell->accessibility_delegate()->TriggerAccessibilityAlert(
+      A11Y_ALERT_WINDOW_OVERVIEW_MODE_ENTERED);
 }
 
 WindowOverview::~WindowOverview() {
@@ -254,11 +250,6 @@ void WindowOverview::OnWindowsChanged() {
   PositionWindows(/* animate */ true);
 }
 
-void WindowOverview::MoveToSingleRootWindow(aura::Window* root_window) {
-  single_root_window_ = root_window;
-  PositionWindows(/* animate */ true);
-}
-
 void WindowOverview::OnKeyEvent(ui::KeyEvent* event) {
   if (GetTargetedWindow(static_cast<aura::Window*>(event->target())))
     event->StopPropagation();
@@ -378,18 +369,9 @@ void WindowOverview::HideAndTrackNonOverviewWindows() {
 }
 
 void WindowOverview::PositionWindows(bool animate) {
-  if (single_root_window_) {
-    std::vector<WindowSelectorItem*> windows;
-    for (WindowSelectorItemList::iterator iter = windows_->begin();
-         iter != windows_->end(); ++iter) {
-      windows.push_back(*iter);
-    }
-    PositionWindowsOnRoot(single_root_window_, windows, animate);
-  } else {
-    aura::Window::Windows root_window_list = Shell::GetAllRootWindows();
-    for (size_t i = 0; i < root_window_list.size(); ++i)
-      PositionWindowsFromRoot(root_window_list[i], animate);
-  }
+  aura::Window::Windows root_window_list = Shell::GetAllRootWindows();
+  for (size_t i = 0; i < root_window_list.size(); ++i)
+    PositionWindowsFromRoot(root_window_list[i], animate);
 }
 
 void WindowOverview::PositionWindowsFromRoot(aura::Window* root_window,
@@ -400,13 +382,7 @@ void WindowOverview::PositionWindowsFromRoot(aura::Window* root_window,
     if ((*iter)->GetRootWindow() == root_window)
       windows.push_back(*iter);
   }
-  PositionWindowsOnRoot(root_window, windows, animate);
-}
 
-void WindowOverview::PositionWindowsOnRoot(
-    aura::Window* root_window,
-    const std::vector<WindowSelectorItem*>& windows,
-    bool animate) {
   if (windows.empty())
     return;
 
@@ -455,9 +431,7 @@ void WindowOverview::InitializeSelectionWidget() {
   params.keep_on_top = false;
   params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
   params.opacity = views::Widget::InitParams::OPAQUE_WINDOW;
-  params.parent = Shell::GetContainer(single_root_window_
-                                          ? single_root_window_
-                                          : windows_->front()->GetRootWindow(),
+  params.parent = Shell::GetContainer(windows_->front()->GetRootWindow(),
                                       kShellWindowId_DefaultContainer);
   params.accept_events = false;
   selection_widget_->set_focus_on_creation(false);

ash/wm/overview/window_overview.h

@@ -47,8 +47,7 @@ class WindowOverview : public ui::EventHandler,
   // If |single_root_window| is not NULL, all windows will be positioned on the
   // given root window.
   WindowOverview(WindowSelector* window_selector,
-                 WindowSelectorItemList* windows,
-                 aura::Window* single_root_window);
+                 WindowSelectorItemList* windows);
   virtual ~WindowOverview();
 
   // Sets the selected window to be the window in position |index|.
@@ -57,9 +56,6 @@ class WindowOverview : public ui::EventHandler,
   // Dispatched when the list of windows has changed.
   void OnWindowsChanged();
 
-  // Moves the overview to only |root_window|.
-  void MoveToSingleRootWindow(aura::Window* root_window);
-
   // ui::EventHandler:
   virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
   virtual void OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
@@ -87,10 +83,6 @@ class WindowOverview : public ui::EventHandler,
   void PositionWindows(bool animate);
   // Position all of the windows from |root_window| on |root_window|.
   void PositionWindowsFromRoot(aura::Window* root_window, bool animate);
-  // Position all of the |windows| to fit on the |root_window|.
-  void PositionWindowsOnRoot(aura::Window* root_window,
-                             const std::vector<WindowSelectorItem*>& windows,
-                             bool animate);
 
   // Creates the selection widget.
   void InitializeSelectionWidget();
@@ -113,11 +105,6 @@ class WindowOverview : public ui::EventHandler,
   // selection changes rows and use a different animation.
   size_t selection_index_;
 
-  // If NULL, each root window displays an overview of the windows in that
-  // display. Otherwise, all windows are in a single overview on
-  // |single_root_window_|.
-  aura::Window* single_root_window_;
-
   // The time when overview was started.
   base::Time overview_start_time_;
 

ash/wm/overview/window_selector.cc

@@ -21,10 +21,7 @@
 #include "base/strings/string_number_conversions.h"
 #include "ui/aura/client/focus_client.h"
 #include "ui/aura/window.h"
-#include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_observer.h"
-#include "ui/events/event.h"
-#include "ui/events/event_handler.h"
 #include "ui/wm/core/window_util.h"
 #include "ui/wm/public/activation_client.h"
 
@@ -74,42 +71,6 @@ struct WindowSelectorItemForRoot
   const aura::Window* root_window;
 };
 
-// Filter to watch for the termination of a keyboard gesture to cycle through
-// multiple windows.
-class WindowSelectorEventFilter : public ui::EventHandler {
- public:
-  WindowSelectorEventFilter(WindowSelector* selector);
-  virtual ~WindowSelectorEventFilter();
-
-  // Overridden from ui::EventHandler:
-  virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
-
- private:
-  // A weak pointer to the WindowSelector which owns this instance.
-  WindowSelector* selector_;
-
-  DISALLOW_COPY_AND_ASSIGN(WindowSelectorEventFilter);
-};
-
-// Watch for all keyboard events by filtering the root window.
-WindowSelectorEventFilter::WindowSelectorEventFilter(WindowSelector* selector)
-    : selector_(selector) {
-  Shell::GetInstance()->AddPreTargetHandler(this);
-}
-
-WindowSelectorEventFilter::~WindowSelectorEventFilter() {
-  Shell::GetInstance()->RemovePreTargetHandler(this);
-}
-
-void WindowSelectorEventFilter::OnKeyEvent(ui::KeyEvent* event) {
-  // Views uses VKEY_MENU for both left and right Alt keys.
-  if (event->key_code() == ui::VKEY_MENU &&
-      event->type() == ui::ET_KEY_RELEASED) {
-    selector_->SelectWindow();
-    // Warning: |this| will be deleted from here on.
-  }
-}
-
 // Triggers a shelf visibility update on all root window controllers.
 void UpdateShelfVisibility() {
   Shell::RootWindowControllerList root_window_controllers =
@@ -121,110 +82,11 @@ void UpdateShelfVisibility() {
   }
 }
 
-// Returns the window immediately below |window| in the current container.
-aura::Window* GetWindowBelow(aura::Window* window) {
-  aura::Window* parent = window->parent();
-  if (!parent)
-    return NULL;
-  aura::Window* below = NULL;
-  for (aura::Window::Windows::const_iterator iter = parent->children().begin();
-       iter != parent->children().end(); ++iter) {
-    if (*iter == window)
-      return below;
-    below = *iter;
-  }
-  NOTREACHED();
-  return NULL;
-}
-
 }  // namespace
 
-// This class restores and moves a window to the front of the stacking order for
-// the duration of the class's scope.
-class ScopedShowWindow : public aura::WindowObserver {
- public:
-  ScopedShowWindow();
-  virtual ~ScopedShowWindow();
-
-  // Show |window| at the top of the stacking order.
-  void Show(aura::Window* window);
-
-  // Cancel restoring the window on going out of scope.
-  void CancelRestore();
-
-  aura::Window* window() { return window_; }
-
-  // aura::WindowObserver:
-  virtual void OnWillRemoveWindow(aura::Window* window) OVERRIDE;
-
- private:
-  // The window being shown.
-  aura::Window* window_;
-
-  // The window immediately below where window_ belongs.
-  aura::Window* stack_window_above_;
-
-  // If true, minimize window_ on going out of scope.
-  bool minimized_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedShowWindow);
-};
-
-ScopedShowWindow::ScopedShowWindow()
-    : window_(NULL),
-      stack_window_above_(NULL),
-      minimized_(false) {
-}
-
-void ScopedShowWindow::Show(aura::Window* window) {
-  DCHECK(!window_);
-  window_ = window;
-  stack_window_above_ = GetWindowBelow(window);
-  minimized_ = wm::GetWindowState(window)->IsMinimized();
-  window_->parent()->AddObserver(this);
-  window_->Show();
-  wm::GetWindowState(window_)->Activate();
-}
-
-ScopedShowWindow::~ScopedShowWindow() {
-  if (window_) {
-    window_->parent()->RemoveObserver(this);
-
-    // Restore window's stacking position.
-    if (stack_window_above_)
-      window_->parent()->StackChildAbove(window_, stack_window_above_);
-    else
-      window_->parent()->StackChildAtBottom(window_);
-
-    // Restore minimized state.
-    if (minimized_)
-      wm::GetWindowState(window_)->Minimize();
-  }
-}
-
-void ScopedShowWindow::CancelRestore() {
-  if (!window_)
-    return;
-  window_->parent()->RemoveObserver(this);
-  window_ = stack_window_above_ = NULL;
-}
-
-void ScopedShowWindow::OnWillRemoveWindow(aura::Window* window) {
-  if (window == window_) {
-    CancelRestore();
-  } else if (window == stack_window_above_) {
-    // If the window this window was above is removed, use the next window down
-    // as the restore marker.
-    stack_window_above_ = GetWindowBelow(stack_window_above_);
-  }
-}
-
 WindowSelector::WindowSelector(const WindowList& windows,
-                               WindowSelector::Mode mode,
                                WindowSelectorDelegate* delegate)
-    : mode_(mode),
-      delegate_(delegate),
-      selected_window_(0),
+    : delegate_(delegate),
       restore_focus_window_(aura::client::GetFocusClient(
           Shell::GetPrimaryRootWindow())->GetFocusedWindow()),
       ignore_activations_(false) {
@@ -280,12 +142,7 @@ WindowSelector::WindowSelector(const WindowList& windows,
     }
   }
 
-  if (mode == WindowSelector::CYCLE) {
-    cycle_start_time_ = base::Time::Now();
-    event_handler_.reset(new WindowSelectorEventFilter(this));
-  } else {
-    StartOverview();
-  }
+  StartOverview();
 }
 
 WindowSelector::~WindowSelector() {
@@ -300,45 +157,10 @@ WindowSelector::~WindowSelector() {
   // Clearing the window list resets the ignored_by_shelf flag on the windows.
   windows_.clear();
   UpdateShelfVisibility();
-
-  if (!cycle_start_time_.is_null()) {
-    UMA_HISTOGRAM_MEDIUM_TIMES("Ash.WindowSelector.CycleTime",
-        base::Time::Now() - cycle_start_time_);
-  }
-}
-
-void WindowSelector::Step(WindowSelector::Direction direction) {
-  DCHECK(!windows_.empty());
-  // Upgrade to CYCLE mode if currently in OVERVIEW mode.
-  if (mode_ != CYCLE) {
-    event_handler_.reset(new WindowSelectorEventFilter(this));
-    DCHECK(window_overview_);
-    // Set the initial selection window to animate to the new selection.
-    window_overview_->SetSelection(selected_window_);
-    window_overview_->MoveToSingleRootWindow(
-        windows_[selected_window_]->GetRootWindow());
-    mode_ = CYCLE;
-  }
-
-  selected_window_ = (selected_window_ + windows_.size() +
-      (direction == WindowSelector::FORWARD ? 1 : -1)) % windows_.size();
-  if (window_overview_) {
-    window_overview_->SetSelection(selected_window_);
-  } else {
-    base::AutoReset<bool> restoring_focus(&ignore_activations_, true);
-    showing_window_.reset(new ScopedShowWindow);
-    showing_window_->Show(windows_[selected_window_]->SelectionWindow());
-  }
-}
-
-void WindowSelector::SelectWindow() {
-  SelectWindow(windows_[selected_window_]->SelectionWindow());
 }
 
 void WindowSelector::SelectWindow(aura::Window* window) {
   ResetFocusRestoreWindow(false);
-  if (showing_window_ && showing_window_->window() == window)
-    showing_window_->CancelRestore();
   ScopedVector<WindowSelectorItem>::iterator iter =
       std::find_if(windows_.begin(), windows_.end(),
                    WindowSelectorItemTargetComparator(window));
@@ -388,7 +210,6 @@ void WindowSelector::OnWindowDestroying(aura::Window* window) {
   if (!(*iter)->empty())
     return;
 
-  size_t deleted_index = iter - windows_.begin();
   windows_.erase(iter);
   if (windows_.empty()) {
     CancelSelection();
@@ -396,13 +217,6 @@ void WindowSelector::OnWindowDestroying(aura::Window* window) {
   }
   if (window_overview_)
     window_overview_->OnWindowsChanged();
-  if (mode_ == CYCLE && selected_window_ >= deleted_index) {
-    if (selected_window_ > deleted_index)
-      selected_window_--;
-    selected_window_ = selected_window_ % windows_.size();
-    if (window_overview_)
-      window_overview_->SetSelection(selected_window_);
-  }
 }
 
 void WindowSelector::OnWindowBoundsChanged(aura::Window* window,
@@ -449,12 +263,7 @@ void WindowSelector::StartOverview() {
   aura::client::GetFocusClient(
       Shell::GetPrimaryRootWindow())->FocusWindow(NULL);
 
-  aura::Window* overview_root = NULL;
-  if (mode_ == CYCLE)
-    overview_root = windows_[selected_window_]->GetRootWindow();
-  window_overview_.reset(new WindowOverview(this, &windows_, overview_root));
-  if (mode_ == CYCLE)
-    window_overview_->SetSelection(selected_window_);
+  window_overview_.reset(new WindowOverview(this, &windows_));
   UpdateShelfVisibility();
 }
 

ash/wm/overview/window_selector.h

@@ -20,54 +20,30 @@ namespace aura {
 class RootWindow;
 }
 
-namespace ui {
-class EventHandler;
-}
-
 namespace ash {
-class ScopedShowWindow;
 class WindowOverview;
 class WindowSelectorDelegate;
 class WindowSelectorItem;
 class WindowSelectorTest;
 
-// The WindowSelector allows selecting a window by alt-tabbing (CYCLE mode) or
-// by clicking or tapping on it (OVERVIEW mode). A WindowOverview will be shown
-// in OVERVIEW mode or if the user lingers on a window while alt tabbing.
+// The WindowSelector allows selecting a window by clicking or tapping on it
+// (entering Overview Mode).
 class ASH_EXPORT WindowSelector
     : public aura::WindowObserver,
       public aura::client::ActivationChangeObserver {
  public:
-  enum Direction {
-    FORWARD,
-    BACKWARD
-  };
-  enum Mode {
-    CYCLE,
-    OVERVIEW
-  };
-
   typedef std::vector<aura::Window*> WindowList;
 
   WindowSelector(const WindowList& windows,
-                 Mode mode,
                  WindowSelectorDelegate* delegate);
   virtual ~WindowSelector();
 
-  // Step to the next window in |direction|.
-  void Step(Direction direction);
-
-  // Choose the currently selected window.
-  void SelectWindow();
-
   // Choose |window| from the available windows to select.
   void SelectWindow(aura::Window* window);
 
   // Cancels window selection.
   void CancelSelection();
 
-  Mode mode() { return mode_; }
-
   // aura::WindowObserver:
   virtual void OnWindowAdded(aura::Window* new_window) OVERRIDE;
   virtual void OnWindowBoundsChanged(aura::Window* window,
@@ -99,29 +75,12 @@ class ASH_EXPORT WindowSelector
   // Tracks observed windows.
   std::set<aura::Window*> observed_windows_;
 
-  // The window selection mode.
-  Mode mode_;
-
-  // An event handler listening for the release of the alt key during alt-tab
-  // cycling.
-  scoped_ptr<ui::EventHandler> event_handler_;
-
-  // The currently selected window being shown (temporarily brought to the front
-  // of the stacking order and made visible).
-  scoped_ptr<ScopedShowWindow> showing_window_;
-
   scoped_ptr<WindowOverview> window_overview_;
 
-  // The time when window cycling was started.
-  base::Time cycle_start_time_;
-
   // Weak pointer to the selector delegate which will be called when a
   // selection is made.
   WindowSelectorDelegate* delegate_;
 
-  // Index of the currently selected window if the mode is CYCLE.
-  size_t selected_window_;
-
   // A weak pointer to the window which was focused on beginning window
   // selection. If window selection is canceled the focus should be restored to
   // this window.

ash/wm/overview/window_selector_controller.cc

@@ -50,31 +50,11 @@ void WindowSelectorController::ToggleOverview() {
     if (windows.empty())
       return;
 
-    window_selector_.reset(
-        new WindowSelector(windows, WindowSelector::OVERVIEW, this));
+    window_selector_.reset(new WindowSelector(windows, this));
     OnSelectionStarted();
   }
 }
 
-void WindowSelectorController::HandleCycleWindow(
-    WindowSelector::Direction direction) {
-  if (!CanSelect())
-    return;
-
-  if (!IsSelecting()) {
-    std::vector<aura::Window*> windows = ash::Shell::GetInstance()->
-        mru_window_tracker()->BuildMruWindowList();
-    // Don't cycle with no windows.
-    if (windows.empty())
-      return;
-
-    window_selector_.reset(
-        new WindowSelector(windows, WindowSelector::CYCLE, this));
-    OnSelectionStarted();
-  }
-  window_selector_->Step(direction);
-}
-
 bool WindowSelectorController::IsSelecting() {
   return window_selector_.get() != NULL;
 }

ash/wm/overview/window_selector_controller.h

@@ -41,11 +41,6 @@ class ASH_EXPORT WindowSelectorController
   // or touch rather than keypresses.
   void ToggleOverview();
 
-  // Cycles between windows in the given |direction|. It is assumed that the
-  // alt key is held down and a key filter is installed to watch for alt being
-  // released.
-  void HandleCycleWindow(WindowSelector::Direction direction);
-
   // Returns true if window selection mode is active.
   bool IsSelecting();
 

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/session/session_state_delegate.h"
+#include "ash/shell.h"
+#include "ash/wm/mru_window_tracker.h"
+#include "ash/wm/window_cycle_list.h"
+#include "ui/events/event.h"
+#include "ui/events/event_handler.h"
+
+namespace ash {
+
+namespace {
+
+// Filter to watch for the termination of a keyboard gesture to cycle through
+// multiple windows.
+class WindowCycleEventFilter : public ui::EventHandler {
+ public:
+  WindowCycleEventFilter();
+  virtual ~WindowCycleEventFilter();
+
+  // Overridden from ui::EventHandler:
+  virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WindowCycleEventFilter);
+};
+
+WindowCycleEventFilter::WindowCycleEventFilter() {
+  Shell::GetInstance()->AddPreTargetHandler(this);
+}
+
+WindowCycleEventFilter::~WindowCycleEventFilter() {
+  Shell::GetInstance()->RemovePreTargetHandler(this);
+}
+
+void WindowCycleEventFilter::OnKeyEvent(ui::KeyEvent* event) {
+  // Views uses VKEY_MENU for both left and right Alt keys.
+  if (event->key_code() == ui::VKEY_MENU &&
+      event->type() == ui::ET_KEY_RELEASED) {
+    Shell::GetInstance()->window_cycle_controller()->StopCycling();
+    // Warning: |this| will be deleted from here on.
+  }
+}
+
+}  // namespace
+
+//////////////////////////////////////////////////////////////////////////////
+// WindowCycleController, public:
+
+WindowCycleController::WindowCycleController() {
+}
+
+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() &&
+         !Shell::GetInstance()->IsSystemModalWindowOpen();
+}
+
+void WindowCycleController::HandleCycleWindow(Direction direction) {
+  if (!CanCycle())
+    return;
+
+  if (!IsCycling())
+    StartCycling();
+
+  Step(direction);
+}
+
+void WindowCycleController::StartCycling() {
+  window_cycle_list_.reset(new WindowCycleList(ash::Shell::GetInstance()->
+      mru_window_tracker()->BuildMruWindowList()));
+  event_handler_.reset(new WindowCycleEventFilter());
+}
+
+//////////////////////////////////////////////////////////////////////////////
+// WindowCycleController, private:
+
+void WindowCycleController::Step(Direction direction) {
+  DCHECK(window_cycle_list_.get());
+  window_cycle_list_->Step(direction);
+}
+
+void WindowCycleController::StopCycling() {
+  window_cycle_list_.reset();
+  // Remove our key event filter.
+  event_handler_.reset();
+}
+
+}  // namespace ash

ash/wm/window_cycle_controller.h

+// 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.
+
+#ifndef ASH_WM_WINDOW_CYCLE_CONTROLLER_H_
+#define ASH_WM_WINDOW_CYCLE_CONTROLLER_H_
+
+#include "ash/ash_export.h"
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace ui {
+class EventHandler;
+}
+
+namespace ash {
+
+class WindowCycleList;
+
+// Controls cycling through windows with the keyboard via alt-tab.
+// Windows are sorted primarily by most recently used, and then by screen order.
+// We activate windows as you cycle through them, so the order on the screen
+// may change during the gesture, but the most recently used list isn't updated
+// until the cycling ends.  Thus we maintain the state of the windows
+// at the beginning of the gesture so you can cycle through in a consistent
+// order.
+class ASH_EXPORT WindowCycleController {
+ public:
+  enum Direction {
+    FORWARD,
+    BACKWARD
+  };
+
+  WindowCycleController();
+  virtual ~WindowCycleController();
+
+  // Returns true if cycling through windows is enabled. This is false at
+  // certain times, such as when the lock screen is visible.
+  static bool CanCycle();
+
+  // Cycles between windows in the given |direction|.
+  void HandleCycleWindow(Direction direction);
+
+  // Returns true if we are in the middle of a window cycling gesture.
+  bool IsCycling() const { return window_cycle_list_.get() != NULL; }
+
+  // Call to start cycling windows. This funtion adds a pre-target handler to
+  // listen to the alt key release.
+  void StartCycling();
+
+  // Stops the current window cycle and removes the event filter.
+  void StopCycling();
+
+  // Returns the WindowCycleList. Really only useful for testing.
+  const WindowCycleList* window_cycle_list() const {
+    return window_cycle_list_.get();
+  }
+
+ private:
+  // Cycles to the next or previous window based on |direction|.
+  void Step(Direction direction);
+
+  scoped_ptr<WindowCycleList> window_cycle_list_;
+
+  // Event handler to watch for release of alt key.
+  scoped_ptr<ui::EventHandler> event_handler_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowCycleController);
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_WINDOW_CYCLE_CONTROLLER_H_

ash/wm/window_cycle_list.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_list.h"
+
+#include "ash/shell.h"
+#include "ash/wm/mru_window_tracker.h"
+#include "ash/wm/window_animations.h"
+#include "ash/wm/window_state.h"
+#include "ash/wm/window_util.h"
+#include "ui/aura/window.h"
+
+namespace ash {
+
+// Returns the window immediately below |window| in the current container.
+aura::Window* GetWindowBelow(aura::Window* window) {
+  aura::Window* parent = window->parent();
+  if (!parent)
+    return NULL;
+  aura::Window::Windows::const_iterator iter =
+      std::find(parent->children().begin(), parent->children().end(), window);
+  CHECK(*iter == window);
+  if (iter != parent->children().begin())
+    return *(iter - 1);
+  else
+    return NULL;
+}
+
+// This class restores and moves a window to the front of the stacking order for
+// the duration of the class's scope.
+class ScopedShowWindow : public aura::WindowObserver {
+ public:
+  ScopedShowWindow();
+  virtual ~ScopedShowWindow();
+
+  // Show |window| at the top of the stacking order.
+  void Show(aura::Window* window);
+
+  // Cancel restoring the window on going out of scope.
+  void CancelRestore();
+
+  aura::Window* window() { return window_; }
+
+  // aura::WindowObserver:
+  virtual void OnWillRemoveWindow(aura::Window* window) OVERRIDE;
+
+ private:
+  // The window being shown.
+  aura::Window* window_;
+
+  // The window immediately below where window_ belongs.
+  aura::Window* stack_window_above_;
+
+  // If true, minimize window_ on going out of scope.
+  bool minimized_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedShowWindow);
+};
+
+ScopedShowWindow::ScopedShowWindow()
+    : window_(NULL),
+      stack_window_above_(NULL),
+      minimized_(false) {
+}
+
+ScopedShowWindow::~ScopedShowWindow() {
+  if (window_) {
+    window_->parent()->RemoveObserver(this);
+
+    // Restore window's stacking position.
+    if (stack_window_above_)
+      window_->parent()->StackChildAbove(window_, stack_window_above_);
+    else
+      window_->parent()->StackChildAtBottom(window_);
+
+    // Restore minimized state.
+    if (minimized_)
+      wm::GetWindowState(window_)->Minimize();
+  }
+}
+
+void ScopedShowWindow::Show(aura::Window* window) {
+  DCHECK(!window_);
+  window_ = window;
+  stack_window_above_ = GetWindowBelow(window);
+  minimized_ = wm::GetWindowState(window)->IsMinimized();
+  window_->parent()->AddObserver(this);
+  window_->Show();
+  wm::GetWindowState(window_)->Activate();
+}
+
+void ScopedShowWindow::CancelRestore() {
+  if (!window_)
+    return;
+  window_->parent()->RemoveObserver(this);
+  window_ = stack_window_above_ = NULL;
+}
+
+void ScopedShowWindow::OnWillRemoveWindow(aura::Window* window) {
+  if (window == window_) {
+    CancelRestore();
+  } else if (window == stack_window_above_) {
+    // If the window this window was above is removed, use the next window down
+    // as the restore marker.
+    stack_window_above_ = GetWindowBelow(stack_window_above_);
+  }
+}
+
+WindowCycleList::WindowCycleList(const WindowList& windows)
+    : windows_(windows),
+      current_index_(0) {
+  ash::Shell::GetInstance()->mru_window_tracker()->SetIgnoreActivations(true);
+
+  for (WindowList::const_iterator i = windows_.begin(); i != windows_.end();
+       ++i) {
+    (*i)->AddObserver(this);
+  }
+}
+
+WindowCycleList::~WindowCycleList() {
+  ash::Shell::GetInstance()->mru_window_tracker()->SetIgnoreActivations(false);
+  for (WindowList::const_iterator i = windows_.begin(); i != windows_.end();
+       ++i) {
+    (*i)->RemoveObserver(this);
+  }
+  if (showing_window_)
+    showing_window_->CancelRestore();
+}
+
+void WindowCycleList::Step(WindowCycleController::Direction direction) {
+  if (windows_.empty())
+    return;
+
+  // When there is only one window, we should give feedback to the user. If the
+  // window is minimized, we should also show it.
+  if (windows_.size() == 1) {
+    ::wm::AnimateWindow(windows_[0], ::wm::WINDOW_ANIMATION_TYPE_BOUNCE);
+    windows_[0]->Show();
+    wm::GetWindowState(windows_[0])->Activate();
+    return;
+  }
+
+  DCHECK(static_cast<size_t>(current_index_) < windows_.size());
+
+  // We're in a valid cycle, so step forward or backward.
+  current_index_ += direction == WindowCycleController::FORWARD ? 1 : -1;
+
+  // Wrap to window list size.
+  current_index_ = (current_index_ + windows_.size()) % windows_.size();
+  DCHECK(windows_[current_index_]);
+
+  // Make sure the next window is visible.
+  showing_window_.reset(new ScopedShowWindow);
+  showing_window_->Show(windows_[current_index_]);
+}
+
+void WindowCycleList::OnWindowDestroyed(aura::Window* window) {
+  window->RemoveObserver(this);
+
+  WindowList::iterator i = std::find(windows_.begin(), windows_.end(), window);
+  DCHECK(i != windows_.end());
+  int removed_index = static_cast<int>(i - windows_.begin());
+  windows_.erase(i);
+  if (current_index_ > removed_index ||
+      current_index_ == static_cast<int>(windows_.size())) {
+    current_index_--;
+  }
+}
+
+}  // namespace ash

ash/wm/window_cycle_list.h

+// 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.
+
+#ifndef ASH_WM_WINDOW_CYCLE_LIST_H_
+#define ASH_WM_WINDOW_CYCLE_LIST_H_
+
+#include <vector>
+
+#include "ash/ash_export.h"
+#include "ash/wm/window_cycle_controller.h"
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/aura/window_observer.h"
+
+namespace ash {
+
+class ScopedShowWindow;
+
+// Tracks a set of Windows that can be stepped through. This class is used by
+// the WindowCycleController.
+class ASH_EXPORT WindowCycleList : public aura::WindowObserver {
+ public:
+  typedef std::vector<aura::Window*> WindowList;
+
+  explicit WindowCycleList(const WindowList& windows);
+  virtual ~WindowCycleList();
+
+  bool empty() const { return windows_.empty(); }
+
+  // Cycles to the next or previous window based on |direction|.
+  void Step(WindowCycleController::Direction direction);
+
+  const WindowList& windows() const { return windows_; }
+
+ private:
+  // aura::WindowObserver overrides:
+  // There is a chance a window is destroyed, for example by JS code. We need to
+  // take care of that even if it is not intended for the user to close a window
+  // while window cycling.
+  virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE;
+
+  // List of weak pointers to windows to use while cycling with the keyboard.
+  // List is built when the user initiates the gesture (i.e. hits alt-tab the
+  // first time) and is emptied when the gesture is complete (i.e. releases the
+  // alt key).
+  WindowList windows_;
+
+  // Current position in the |windows_|
+  int current_index_;
+
+  // Wrapper for the window brought to the front.
+  scoped_ptr<ScopedShowWindow> showing_window_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowCycleList);
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_WINDOW_CYCLE_LIST_H_