Move event handler to window_selector to ensure correct lifetime.

BUG=279562
TEST=With --ash-enable-overview-mode, start alt-tabbing, click a window, then press and release alt. There should be no crash.

Review URL: https://chromiumcodereview.appspot.com/23529006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221123 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 49 insertions, 57 deletions

diff --git a/ash/wm/overview/window_selector.cc b/ash/wm/overview/window_selector.cc
index 0118e5d..a39c145 100644
--- a/ash/wm/overview/window_selector.cc
+++ b/ash/wm/overview/window_selector.cc
@@ -17,6 +17,8 @@
 #include "ui/aura/client/focus_client.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
+#include "ui/base/events/event.h"
+#include "ui/base/events/event_handler.h"
 
 namespace ash {
 
@@ -38,6 +40,42 @@ struct WindowSelectorWindowComparator
   const aura::Window* target;
 };
 
+// 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.
+  }
+}
+
 }  // namespace
 
 WindowSelector::WindowSelector(const WindowList& windows,
@@ -73,10 +111,12 @@ WindowSelector::WindowSelector(const WindowList& windows,
     }
   }
 
-  if (mode == WindowSelector::CYCLE)
+  if (mode == WindowSelector::CYCLE) {
+    event_handler_.reset(new WindowSelectorEventFilter(this));
     start_overview_timer_.Reset();
-  else
+  } else {
     StartOverview();
+  }
 }
 
 WindowSelector::~WindowSelector() {
diff --git a/ash/wm/overview/window_selector.h b/ash/wm/overview/window_selector.h
index 7536f41..4059540 100644
--- a/ash/wm/overview/window_selector.h
+++ b/ash/wm/overview/window_selector.h
@@ -20,7 +20,7 @@ class RootWindow;
 }
 
 namespace ui {
-class LocatedEvent;
+class EventHandler;
 }
 
 namespace ash {
@@ -101,6 +101,10 @@ class ASH_EXPORT WindowSelector
   // 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_;
+
   base::DelayTimer<WindowSelector> start_overview_timer_;
   scoped_ptr<WindowOverview> window_overview_;
 
diff --git a/ash/wm/overview/window_selector_controller.cc b/ash/wm/overview/window_selector_controller.cc
index 490e570..84c83d2 100644
--- a/ash/wm/overview/window_selector_controller.cc
+++ b/ash/wm/overview/window_selector_controller.cc
@@ -9,47 +9,9 @@
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/overview/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() {
 }
 
@@ -86,7 +48,6 @@ void WindowSelectorController::HandleCycleWindow(
     return;
 
   if (!IsSelecting()) {
-    event_handler_.reset(new WindowSelectorEventFilter());
     std::vector<aura::Window*> windows = ash::Shell::GetInstance()->
         mru_window_tracker()->BuildMruWindowList();
     // Removing focus will hide popup windows like the omnibar or open menus.
@@ -98,11 +59,6 @@ void WindowSelectorController::HandleCycleWindow(
   }
 }
 
-void WindowSelectorController::AltKeyReleased() {
-  event_handler_.reset();
-  window_selector_->SelectWindow();
-}
-
 bool WindowSelectorController::IsSelecting() {
   return window_selector_.get() != NULL;
 }
diff --git a/ash/wm/overview/window_selector_controller.h b/ash/wm/overview/window_selector_controller.h
index 6f03de6..6b16892 100644
--- a/ash/wm/overview/window_selector_controller.h
+++ b/ash/wm/overview/window_selector_controller.h
@@ -19,10 +19,6 @@ namespace aura {
 class Window;
 }
 
-namespace ui {
-class EventHandler;
-}
-
 namespace ash {
 
 namespace internal {
@@ -53,10 +49,6 @@ class ASH_EXPORT WindowSelectorController
   // released.
   void HandleCycleWindow(WindowSelector::Direction direction);
 
-  // Informs the controller that the Alt key has been released and it can
-  // terminate the existing multi-step cycle.
-  void AltKeyReleased();
-
   // Returns true if window selection mode is active.
   bool IsSelecting();
 
@@ -68,7 +60,6 @@ class ASH_EXPORT WindowSelectorController
   friend class internal::WindowSelectorTest;
 
   scoped_ptr<WindowSelector> window_selector_;
-  scoped_ptr<ui::EventHandler> event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowSelectorController);
 };
diff --git a/ash/wm/overview/window_selector_unittest.cc b/ash/wm/overview/window_selector_unittest.cc
index d9a3d61..3210259 100644
--- a/ash/wm/overview/window_selector_unittest.cc
+++ b/ash/wm/overview/window_selector_unittest.cc
@@ -54,7 +54,8 @@ class WindowSelectorTest : public test::AshTestBase {
   }
 
   void StopCycling() {
-    ash::Shell::GetInstance()->window_selector_controller()->AltKeyReleased();
+    ash::Shell::GetInstance()->window_selector_controller()->window_selector_->
+        SelectWindow();
   }
 
   void FireOverviewStartTimer() {