Add checks to verify that all observed_windows_ are targeted in overview windows_.

ash/wm/overview/window_selector.cc

Index: ash/wm/overview/window_selector.cc
diff --git a/ash/wm/overview/window_selector.cc b/ash/wm/overview/window_selector.cc
index d9903da69c51d9925d578a3cc58028ea9021f37c..79d428f2040cc170a41cd8b9b93f2f734b1d9ea0 100644
--- a/ash/wm/overview/window_selector.cc
+++ b/ash/wm/overview/window_selector.cc
@@ -256,6 +256,7 @@ WindowSelector::WindowSelector(const WindowList& windows,
 
   std::vector<WindowSelectorPanels*> panels_items;
   for (size_t i = 0; i < windows.size(); ++i) {
+    WindowSelectorItem* item = NULL;
     if (windows[i] != restore_focus_window_)
       windows[i]->AddObserver(this);
     observed_windows_.insert(windows[i]);
@@ -276,9 +277,13 @@ WindowSelector::WindowSelector(const WindowList& windows,
         panels_item = *iter;
       }
       panels_item->AddWindow(windows[i]);
+      item = panels_item;
     } else {
-      windows_.push_back(new WindowSelectorWindow(windows[i]));
+      item = new WindowSelectorWindow(windows[i]);
+      windows_.push_back(item);
     }
+    // Verify that the window has been added to an item in overview.
+    CHECK(item->TargetedWindow(windows[i]));
   }
   UMA_HISTOGRAM_COUNTS_100("Ash.WindowSelector.Items", windows_.size());
 
@@ -396,8 +401,11 @@ void WindowSelector::OnWindowDestroying(aura::Window* window) {
   window->RemoveObserver(this);
   if (window == restore_focus_window_)
     restore_focus_window_ = NULL;
-  if (iter == windows_.end())
+  if (iter == windows_.end()) {
+    CHECK(std::find(observed_windows_.begin(),
+              observed_windows_.end(), window) == observed_windows_.end());
     return;
+  }
 
   observed_windows_.erase(window);

[flackr, 2013/11/22 22:42:34]

I could alternately move this line up before the early exit to guarantee that we
don't call RemoveObserver on any observed window which is destroyed, but it
should be in the windows_ list so this seems more like a workaround.

   (*iter)->RemoveWindow(window);