Fix crash which occurs when a widget destroys itself as a result of ET_GESTURE_TAP_DOWN

ash/wm/caption_buttons/frame_maximize_button.cc

Index: ash/wm/caption_buttons/frame_maximize_button.cc
diff --git a/ash/wm/caption_buttons/frame_maximize_button.cc b/ash/wm/caption_buttons/frame_maximize_button.cc
index 16b98fecdee84b398995454bf3cef92b28e0e312..93dcb207665df7fd75cd209caef6dcc4b92ef544 100644
--- a/ash/wm/caption_buttons/frame_maximize_button.cc
+++ b/ash/wm/caption_buttons/frame_maximize_button.cc
@@ -38,9 +38,7 @@ const int kUpdateDelayMS = 400;
 // The delay of the bubble appearance.
 const int kBubbleAppearanceDelayMS = 500;
 
-// The minimum sanp size in percent of the screen width.
-const int kMinSnapSizePercent = 50;
-}
+}  // namespace
 
 // EscapeEventFilter is installed on the RootWindow to track when the escape key
 // is pressed. We use an EventFilter for this as the FrameMaximizeButton
@@ -149,10 +147,11 @@ void FrameMaximizeButton::SnapButtonHovered(SnapType type) {
 }
 
 void FrameMaximizeButton::ExecuteSnapAndCloseMenu(SnapType snap_type) {
-  // We can come here with no snap type set in case that the mouse opened the
-  // maximize button and a touch event "touched" a button.
-  if (snap_type_ == SNAP_NONE)
+  if (snap_type_ != snap_type) {
+    // This occurs if mouse hover opened the maximize bubble and a user
+    // "touched" one of the maximize bubble's buttons.
     SnapButtonHovered(snap_type);
+  }
 
   Cancel(true);
   // Tell our menu to close.
@@ -191,12 +190,19 @@ void FrameMaximizeButton::OnWindowDestroying(aura::Window* window) {
   maximizer_.reset();
   if (observing_frame_) {
     CHECK_EQ(frame_->GetNativeWindow(), window);
-    frame_->GetNativeWindow()->RemoveObserver(this);
+    window->RemoveObserver(this);
+    wm::GetWindowState(window)->RemoveObserver(this);
     frame_->RemoveObserver(this);
     observing_frame_ = false;
   }
 }
 
+void FrameMaximizeButton::OnPostWindowShowTypeChange(
+    wm::WindowState* window_state,
+    wm::WindowShowType old_type) {
+  Cancel(false);
+}
+
 void FrameMaximizeButton::OnWidgetActivationChanged(views::Widget* widget,
                                                     bool active) {
   // Upon losing focus, the bubble menu and the phantom window should hide.
@@ -224,7 +230,9 @@ void FrameMaximizeButton::OnMouseEntered(const ui::MouseEvent& event) {
     DCHECK(GetWidget());
     if (!observing_frame_) {
       observing_frame_ = true;
-      frame_->GetNativeWindow()->AddObserver(this);
+      aura::Window* window = frame_->GetNativeWindow();
+      window->AddObserver(this);
+      wm::GetWindowState(window)->AddObserver(this);
       frame_->AddObserver(this);
     }
     maximizer_.reset(new MaximizeBubbleController(
@@ -558,31 +566,23 @@ MaximizeBubbleFrameState
 FrameMaximizeButton::GetMaximizeBubbleFrameState() const {
   wm::WindowState* window_state =
       wm::GetWindowState(frame_->GetNativeWindow());
-  // When there are no restore bounds, we are in normal mode.
-  if (!window_state->HasRestoreBounds())
-    return FRAME_STATE_NONE;
-  // The normal maximized test can be used.
-  if (frame_->IsMaximized())
-    return FRAME_STATE_FULL;
-  // For Left/right maximize we need to check the dimensions.
-  gfx::Rect bounds = frame_->GetWindowBoundsInScreen();
-  gfx::Rect screen = Shell::GetScreen()->GetDisplayNearestWindow(
-      frame_->GetNativeView()).work_area();
-  if (bounds.width() < (screen.width() * kMinSnapSizePercent) / 100)
-    return FRAME_STATE_NONE;
-  // We might still have a horizontally filled window at this point which we
-  // treat as no special state.
-  if (bounds.y() != screen.y() || bounds.height() != screen.height())
-    return FRAME_STATE_NONE;
-
-  // We have to be in a maximize mode at this point.
-  if (bounds.x() == screen.x())
-    return FRAME_STATE_SNAP_LEFT;
-  if (bounds.right() == screen.right())
-    return FRAME_STATE_SNAP_RIGHT;
-  // If we come here, it is likely caused by the fact that the
-  // "VerticalResizeDoubleClick" stored a restore rectangle. In that case
-  // we allow all maximize operations (and keep the restore rectangle).
+  switch (window_state->window_show_type()) {
+    case wm::SHOW_TYPE_MAXIMIZED:
+    case wm::SHOW_TYPE_FULLSCREEN:
+      return FRAME_STATE_FULL;
+    case wm::SHOW_TYPE_LEFT_SNAPPED:
+      return FRAME_STATE_SNAP_LEFT;
+    case wm::SHOW_TYPE_RIGHT_SNAPPED:
+      return FRAME_STATE_SNAP_RIGHT;
+    case wm::SHOW_TYPE_DEFAULT:
+    case wm::SHOW_TYPE_NORMAL:
+    case wm::SHOW_TYPE_MINIMIZED:
+    case wm::SHOW_TYPE_INACTIVE:
+    case wm::SHOW_TYPE_DETACHED:
+    case wm::SHOW_TYPE_END:
+    case wm::SHOW_TYPE_AUTO_POSITIONED:
+      return FRAME_STATE_NONE;
+  }
   return FRAME_STATE_NONE;
 }