Release aura::Desktop event handler windows on detaching an ancestor window.

ui/aura/desktop.cc

Index: ui/aura/desktop.cc
diff --git a/ui/aura/desktop.cc b/ui/aura/desktop.cc
index 90ee1716fc309bb76a50e7dfeace8cd369d75bda..53e08fd6cb7b714b4b60bd72d91d4664e14c61c3 100644
--- a/ui/aura/desktop.cc
+++ b/ui/aura/desktop.cc
@@ -100,6 +100,13 @@ void GetEventFiltersToNotify(Window* target, EventFilters* filters) {
   }
 }
 
+// Returns true if |descendant| is a descendant of |ancestor|.
+bool IsAncestor(Window* ancestor, Window* descendant) {
+  while (descendant && descendant != ancestor)
+    descendant = descendant->parent();
+  return descendant == ancestor;

[Ben Goodger (Google), 2011/11/28 17:50:19]

Rather than defining this here, can you add a Contains() method to Window,
similar to Layer's?

[flackr, 2011/11/28 20:36:35]

Done.

+}
+
 }  // namespace
 
 Desktop* Desktop::instance_ = NULL;
@@ -533,19 +540,22 @@ void Desktop::WindowDetachedFromDesktop(Window* detached) {
 
   // If the ancestor of the capture window is detached,
   // release the capture.
-  aura::Window* window = capture_window_;
-  while (window && window != detached)
-    window = window->parent();
-  if (window && window != this)
+  if (IsAncestor(detached, capture_window_) && capture_window_ != this)

[sky, 2011/11/28 17:20:22]

Is the capture_window_ condition necessary? Also, see the DCHECK @ 539.

[flackr, 2011/11/28 20:36:35]

Oops, seems like I converted the old statement incorrectly. In the old code,
after the loop window is either NULL or equal to detached so I should check that
detached != this. Done.

     ReleaseCapture(capture_window_);
 
-  // If the ancestor of the capture window is detached,
+  // If the ancestor of the focused window is detached,
   // release the focus.
-  window = focused_window_;
-  while (window && window != detached)
-    window = window->parent();
-  if (window)
+  if (IsAncestor(detached, focused_window_))
     SetFocusedWindow(NULL);
+
+  // If the ancestor of any event handler windows are detached, release the
+  // pointer to those windows.
+  if (IsAncestor(detached, mouse_pressed_handler_))
+    mouse_pressed_handler_ = NULL;
+  if (IsAncestor(detached, mouse_moved_handler_))
+    mouse_moved_handler_ = NULL;
+  if (IsAncestor(detached, touch_event_handler_))
+    touch_event_handler_ = NULL;
 }
 
 void Desktop::OnLayerAnimationEnded(