Refactor most recently used window tracking into a separate class.

ash/wm/mru_window_tracker.cc

Index: ash/wm/mru_window_tracker.cc
diff --git a/ash/wm/window_cycle_controller.cc b/ash/wm/mru_window_tracker.cc
similarity index 54%
copy from ash/wm/window_cycle_controller.cc
copy to ash/wm/mru_window_tracker.cc
index 89af6c1836f8548ee56c5c4ded9f0eed40dabd9c..06d5bf05eb7d331eda0d8335d765d1f59e773168 100644
--- a/ash/wm/window_cycle_controller.cc
+++ b/ash/wm/mru_window_tracker.cc
@@ -1,8 +1,8 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright (c) 2013 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/wm/mru_window_tracker.h"
 
 #include <algorithm>
 
@@ -21,60 +21,31 @@ namespace ash {
 
 namespace {
 
-// List of containers whose children we will cycle through.
+// List of containers whose children we will allow switching to.
 const int kContainerIds[] = {
   internal::kShellWindowId_DefaultContainer,
   internal::kShellWindowId_AlwaysOnTopContainer
 };
 
-// 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);
-};
-
-// Watch for all keyboard events by filtering the root window.
-WindowCycleEventFilter::WindowCycleEventFilter() {
-}
-
-WindowCycleEventFilter::~WindowCycleEventFilter() {
-}
-
-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()->AltKeyReleased();
-    // Warning: |this| will be deleted from here on.
-  }
-}
-
 // Adds all the children of |window| to |windows|.
 void AddAllChildren(aura::Window* window,
-                    WindowCycleList::WindowList* windows) {
-  const WindowCycleList::WindowList& children(window->children());
+                    MruWindowTracker::WindowList* windows) {
+  const MruWindowTracker::WindowList& children(window->children());
   windows->insert(windows->end(), children.begin(), children.end());
 }
 
 // Adds all the children of all of |window|s children to |windows|.
 void AddWorkspaceChildren(aura::Window* window,
-                          WindowCycleList::WindowList* windows) {
+                          MruWindowTracker::WindowList* windows) {
   for (size_t i = 0; i < window->children().size(); ++i)
     AddAllChildren(window->children()[i], windows);
 }
 
 // Adds the windows that can be cycled through for the specified window id to
 // |windows|.
-void AddCycleWindows(aura::RootWindow* root,
+void AddTrackedWindows(aura::RootWindow* root,
                      int container_id,
-                     WindowCycleList::WindowList* windows) {
+                     MruWindowTracker::WindowList* windows) {
   aura::Window* container = Shell::GetContainer(root, container_id);
   if (container_id == internal::kShellWindowId_DefaultContainer)
     AddWorkspaceChildren(container, windows);
@@ -82,93 +53,14 @@ void AddCycleWindows(aura::RootWindow* root,
     AddAllChildren(container, windows);
 }
 
-}  // namespace
-
-//////////////////////////////////////////////////////////////////////////////
-// WindowCycleController, public:
-
-WindowCycleController::WindowCycleController(
-    aura::client::ActivationClient* activation_client)
-    : activation_client_(activation_client) {
-  activation_client_->AddObserver(this);
-}
-
-WindowCycleController::~WindowCycleController() {
-  Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
-  for (Shell::RootWindowList::const_iterator iter = root_windows.begin();
-       iter != root_windows.end(); ++iter) {
-    for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
-      aura::Window* container = Shell::GetContainer(*iter, kContainerIds[i]);
-      if (container)
-        container->RemoveObserver(this);
-    }
-    aura::Window* default_container =
-        Shell::GetContainer(*iter, internal::kShellWindowId_DefaultContainer);
-    if (default_container) {
-      for (size_t i = 0; i < default_container->children().size(); ++i) {
-        aura::Window* workspace_window = default_container->children()[i];
-        DCHECK_EQ(internal::kShellWindowId_WorkspaceContainer,
-                  workspace_window->id());
-        workspace_window->RemoveObserver(this);
-      }
-    }
-  }
-
-  activation_client_->RemoveObserver(this);
-  StopCycling();
-}
-
-// 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,
-                                              bool is_alt_down) {
-  if (!CanCycle())
-    return;
-
-  if (is_alt_down) {
-    if (!IsCycling()) {
-      // This is the start of an alt-tab cycle through multiple windows, so
-      // listen for the alt key being released to stop cycling.
-      StartCycling();
-      Step(direction);
-      InstallEventFilter();
-    } else {
-      // We're in the middle of an alt-tab cycle, just step forward.
-      Step(direction);
-    }
-  } else {
-    // This is a simple, single-step window cycle.
-    StartCycling();
-    Step(direction);
-    StopCycling();
-  }
-}
-
-void WindowCycleController::HandleLinearCycleWindow() {
-  if (!CanCycle() || IsCycling())
-    return;
-
-  // Use the reversed list of windows to prevent a 2-cycle of the most recent
-  // windows occurring.
-  WindowCycleList cycle_list(BuildWindowList(NULL,true));
-  cycle_list.Step(WindowCycleList::FORWARD);
-}
-
-void WindowCycleController::AltKeyReleased() {
-  StopCycling();
-}
-
-// static
-std::vector<aura::Window*> WindowCycleController::BuildWindowList(
+// Returns a list of windows ordered by their stacking order.
+// If |mru_windows| is passed, these windows are moved to the front of the list.
+// If |top_most_at_end|, the list is returned in descending (bottom-most / least
+// recently used) order.
+MruWindowTracker::WindowList BuildWindowListInternal(
     const std::list<aura::Window*>* mru_windows,
     bool top_most_at_end) {
-  WindowCycleList::WindowList windows;
+  MruWindowTracker::WindowList windows;
   Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
 
   aura::RootWindow* active_root = Shell::GetActiveRootWindow();
@@ -177,16 +69,16 @@ std::vector<aura::Window*> WindowCycleController::BuildWindowList(
     if (*iter == active_root)
       continue;
     for (size_t i = 0; i < arraysize(kContainerIds); ++i)
-      AddCycleWindows(*iter, kContainerIds[i], &windows);
+      AddTrackedWindows(*iter, kContainerIds[i], &windows);
   }
 
   // Add windows in the active root windows last so that the topmost window
   // in the active root window becomes the front of the list.
   for (size_t i = 0; i < arraysize(kContainerIds); ++i)
-    AddCycleWindows(active_root, kContainerIds[i], &windows);
+    AddTrackedWindows(active_root, kContainerIds[i], &windows);
 
   // Removes unfocusable windows.
-  WindowCycleList::WindowList::iterator last =
+  MruWindowTracker::WindowList::iterator last =
       std::remove_if(
           windows.begin(),
           windows.end(),
@@ -200,7 +92,7 @@ std::vector<aura::Window*> WindowCycleController::BuildWindowList(
     for (std::list<aura::Window*>::const_reverse_iterator ix =
          mru_windows->rbegin();
          ix != mru_windows->rend(); ++ix) {
-      WindowCycleList::WindowList::iterator window =
+      MruWindowTracker::WindowList::iterator window =
           std::find(windows.begin(), windows.end(), *ix);
       if (window != windows.end()) {
         windows.erase(window);
@@ -216,7 +108,53 @@ std::vector<aura::Window*> WindowCycleController::BuildWindowList(
   return windows;
 }
 
-void WindowCycleController::OnRootWindowAdded(aura::RootWindow* root_window) {
+}  // namespace
+
+//////////////////////////////////////////////////////////////////////////////
+// MruWindowTracker, public:
+
+MruWindowTracker::MruWindowTracker(
+    aura::client::ActivationClient* activation_client)
+    : activation_client_(activation_client),
+      ignore_window_activations_(false) {
+  activation_client_->AddObserver(this);
+}
+
+MruWindowTracker::~MruWindowTracker() {
+  Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
+  for (Shell::RootWindowList::const_iterator iter = root_windows.begin();
+       iter != root_windows.end(); ++iter) {
+    for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
+      aura::Window* container = Shell::GetContainer(*iter, kContainerIds[i]);
+      if (container)
+        container->RemoveObserver(this);
+    }
+    aura::Window* default_container =
+        Shell::GetContainer(*iter, internal::kShellWindowId_DefaultContainer);
+    if (default_container) {
+      for (size_t i = 0; i < default_container->children().size(); ++i) {
+        aura::Window* workspace_window = default_container->children()[i];
+        DCHECK_EQ(internal::kShellWindowId_WorkspaceContainer,
+                  workspace_window->id());
+        workspace_window->RemoveObserver(this);
+      }
+    }
+  }
+
+  activation_client_->RemoveObserver(this);
+}
+
+// static
+MruWindowTracker::WindowList MruWindowTracker::BuildWindowList(
+    bool top_most_at_end) {
+  return BuildWindowListInternal(NULL, top_most_at_end);
+}
+
+MruWindowTracker::WindowList MruWindowTracker::BuildMruWindowList() {
+  return BuildWindowListInternal(&mru_windows_, false);
+}
+
+void MruWindowTracker::OnRootWindowAdded(aura::RootWindow* root_window) {
   for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
     aura::Window* container =
         Shell::GetContainer(root_window, kContainerIds[i]);
@@ -234,35 +172,23 @@ void WindowCycleController::OnRootWindowAdded(aura::RootWindow* root_window) {
   }
 }
 
-//////////////////////////////////////////////////////////////////////////////
-// WindowCycleController, private:
-
-void WindowCycleController::StartCycling() {
-  windows_.reset(new WindowCycleList(BuildWindowList(&mru_windows_, false)));
-}
-
-void WindowCycleController::Step(Direction direction) {
-  DCHECK(windows_.get());
-  windows_->Step(direction == FORWARD ? WindowCycleList::FORWARD :
-                 WindowCycleList::BACKWARD);
-}
+void MruWindowTracker::SetIgnoreActivations(bool ignore) {
+  ignore_window_activations_ = ignore;
 
-void WindowCycleController::StopCycling() {
-  windows_.reset();
-  // Remove our key event filter.
-  if (event_handler_) {
-    Shell::GetInstance()->RemovePreTargetHandler(event_handler_.get());
-    event_handler_.reset();
+  // If no longer ignoring window activations, move currently active window
+  // to front.
+  if (!ignore) {
+    aura::Window* active_window = wm::GetActiveWindow();
+    mru_windows_.remove(active_window);
+    mru_windows_.push_front(active_window);
   }
-
-  // Add the currently focused window to the MRU list
-  aura::Window* active_window = wm::GetActiveWindow();
-  mru_windows_.remove(active_window);
-  mru_windows_.push_front(active_window);
 }
 
+//////////////////////////////////////////////////////////////////////////////
+// MruWindowTracker, private:
+
 // static
-bool WindowCycleController::IsTrackedContainer(aura::Window* window) {
+bool MruWindowTracker::IsTrackedContainer(aura::Window* window) {
   if (!window)
     return false;
   for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
@@ -273,32 +199,27 @@ bool WindowCycleController::IsTrackedContainer(aura::Window* window) {
   return window->id() == internal::kShellWindowId_WorkspaceContainer;
 }
 
-void WindowCycleController::InstallEventFilter() {
-  event_handler_.reset(new WindowCycleEventFilter());
-  Shell::GetInstance()->AddPreTargetHandler(event_handler_.get());
-}
-
-void WindowCycleController::OnWindowActivated(aura::Window* gained_active,
-                                              aura::Window* lost_active) {
-  if (gained_active && !IsCycling() &&
+void MruWindowTracker::OnWindowActivated(aura::Window* gained_active,
+                                         aura::Window* lost_active) {
+  if (gained_active && !ignore_window_activations_ &&
       IsTrackedContainer(gained_active->parent())) {
     mru_windows_.remove(gained_active);
     mru_windows_.push_front(gained_active);
   }
 }
 
-void WindowCycleController::OnWindowAdded(aura::Window* window) {
+void MruWindowTracker::OnWindowAdded(aura::Window* window) {
   if (window->id() == internal::kShellWindowId_WorkspaceContainer)
     window->AddObserver(this);
 }
 
-void WindowCycleController::OnWillRemoveWindow(aura::Window* window) {
+void MruWindowTracker::OnWillRemoveWindow(aura::Window* window) {
   mru_windows_.remove(window);
   if (window->id() == internal::kShellWindowId_WorkspaceContainer)
     window->RemoveObserver(this);
 }
 
-void WindowCycleController::OnWindowDestroying(aura::Window* window) {
+void MruWindowTracker::OnWindowDestroying(aura::Window* window) {
   window->RemoveObserver(this);
 }