Use overview mode for alt-tab cycling.

ash/wm/window_selector_controller.cc

Index: ash/wm/window_selector_controller.cc
diff --git a/ash/wm/window_selector_controller.cc b/ash/wm/window_selector_controller.cc
index c7fe6966383f3988dc7876fc68e86bb8fe7649c6..e6cd3837a64e5b0241c899ce1317a84d7663d3cb 100644
--- a/ash/wm/window_selector_controller.cc
+++ b/ash/wm/window_selector_controller.cc
@@ -9,9 +9,47 @@
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/window_selector.h"
 #include "ash/wm/window_util.h"
+#include "ui/base/events/event.h"
+#include "ui/base/events/event_handler.h"
 
 namespace ash {
 
+namespace {
+
+// Filter to watch for the termination of a keyboard gesture to cycle through
+// multiple windows.
+class WindowSelectorEventFilter : public ui::EventHandler {
+ public:
+  WindowSelectorEventFilter();
+  virtual ~WindowSelectorEventFilter();
+
+  // Overridden from ui::EventHandler:
+  virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WindowSelectorEventFilter);
+};
+
+// Watch for all keyboard events by filtering the root window.
+WindowSelectorEventFilter::WindowSelectorEventFilter() {
+  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) {
+    Shell::GetInstance()->window_selector_controller()->AltKeyReleased();
+    // Warning: |this| will be deleted from here on.
+  }
+}
+
+}  // namespace
+
 WindowSelectorController::WindowSelectorController() {
 }
 
@@ -41,10 +79,33 @@ void WindowSelectorController::ToggleOverview() {
     aura::Window* active_window = wm::GetActiveWindow();
     if (active_window)
       wm::DeactivateWindow(active_window);
-    window_selector_.reset(new WindowSelector(windows, this));
+    window_selector_.reset(
+        new WindowSelector(windows, WindowSelector::OVERVIEW, this));
+  }
+}
+
+void WindowSelectorController::HandleCycleWindow(
+    WindowSelector::Direction direction) {
+  if (!CanSelect())
+    return;
+
+  if (!IsSelecting()) {
+    event_handler_.reset(new WindowSelectorEventFilter());
+    std::vector<aura::Window*> windows = ash::Shell::GetInstance()->
+        mru_window_tracker()->BuildMruWindowList();
+    window_selector_.reset(
+        new WindowSelector(windows, WindowSelector::CYCLE, this));
+    window_selector_->Step(direction);
+  } else if (window_selector_->mode() == WindowSelector::CYCLE) {
+    window_selector_->Step(direction);
   }
 }
 
+void WindowSelectorController::AltKeyReleased() {
+  event_handler_.reset();
+  window_selector_->SelectWindow();
+}
+
 bool WindowSelectorController::IsSelecting() {
   return window_selector_.get() != NULL;
 }