Update the window labels if they change in overview mode.

ash/wm/overview/window_selector_panels.cc

Index: ash/wm/overview/window_selector_panels.cc
diff --git a/ash/wm/overview/window_selector_panels.cc b/ash/wm/overview/window_selector_panels.cc
index e936f929e31cd702e530efd0845c66b074665309..f70b015649613f19063b13b7c179956a06dabe0a 100644
--- a/ash/wm/overview/window_selector_panels.cc
+++ b/ash/wm/overview/window_selector_panels.cc
@@ -92,10 +92,15 @@ WindowSelectorPanels::~WindowSelectorPanels() {
   static_cast<PanelLayoutManager*>(
       Shell::GetContainer(panels_root_window_, kShellWindowId_PanelContainer)->
           layout_manager())->SetShowCalloutWidgets(true);
+  if (!transform_windows_.empty())
+    transform_windows_[0]->window()->RemoveObserver(this);

[flackr, 2014/06/24 17:10:51]

nit: For consistency use transform_windows_.front() here and elsewhere.

[Nina, 2014/06/24 18:36:28]

Done.

 }
 
 void WindowSelectorPanels::AddWindow(aura::Window* window) {
   DCHECK(window->GetRootWindow() == panels_root_window_);
+  // If this is the panel we use to get the label text, observe it for changes.
+  if (transform_windows_.empty())
+    window->AddObserver(this);
   transform_windows_.push_back(new ScopedTransformPanelWindow(window));
 }
 
@@ -139,6 +144,14 @@ void WindowSelectorPanels::RemoveWindow(const aura::Window* window) {
   for (WindowList::iterator iter = transform_windows_.begin();
        iter != transform_windows_.end(); ++iter) {
     if ((*iter)->window() == window) {
+      // If this is the first window, we are observing it for label changes,
+      // stop doing so before it is destructed.

[flackr, 2014/06/24 17:10:51]

I would also be fine with observing all of the windows but only updating the
label when the window we care about had a title change if it made this simpler.
Eventually I'd like to be able to handle bounds changes and other events in here
rather than having windowselector/windowgrid have to observe every window.

[Nina, 2014/06/24 18:36:28]

Changed the code to observe all of the transform windows, I agree that this does
make it simpler to transition to handling the bounds change in the
WindowSelectorItem.

+      if (window == transform_windows_[0]->window()) {
+        transform_windows_[0]->window()->RemoveObserver(this);
+        // If we still have windows after deletion, observe the next one.
+        if (transform_windows_.size() > 1)
+          transform_windows_[1]->window()->AddObserver(this);
+      }
       (*iter)->OnWindowDestroyed();
       transform_windows_.erase(iter);
       break;