Fix crash when using title drag on a window opened while split view is active

athena/wm/window_manager_impl.cc

Index: athena/wm/window_manager_impl.cc
diff --git a/athena/wm/window_manager_impl.cc b/athena/wm/window_manager_impl.cc
index 2b539612ea6b4ccb29957c61bc33fcae2226d33a..6e42c17a460a350d58e2ef20673ca947b0f2a640 100644
--- a/athena/wm/window_manager_impl.cc
+++ b/athena/wm/window_manager_impl.cc
@@ -101,14 +101,14 @@ void AthenaContainerLayoutManager::OnWindowAddedToLayout(aura::Window* child) {
   aura::Window::Windows list = instance->window_list_provider_->GetWindowList();
   if (std::find(list.begin(), list.end(), child) == list.end())
     return;
-  gfx::Size size;
   if (instance->split_view_controller_->IsSplitViewModeActive()) {
-    size = instance->split_view_controller_->left_window()->bounds().size();
+    instance->split_view_controller_->ReplaceWindow(

[mfomitchev, 2014/09/02 16:23:28]

Hmm.. So normally the two windows shown in split view are the two top-most
windows from WindowListProvider. I think this code may violate this invariant:
Consider the case when left is #1 and right is #2. We add a new window and get:
#1 new_window
#2 left
#3 right
However split view shows new_window and right, not new_window and left.

It seems like we should either update the window order here, or replace window
#3 rather than always replacing left_window. 

This is actually a UX questions which we should perhaps as Kuscher - should we
always replace a fixed position window (e.g. left), or the window which wasn't
the one most recently used.

[mfomitchev, 2014/09/02 16:23:28]

Nit: A short comment explaining that ReplaceWindow will update the
bounds/transform might be useful here

[pkotwicz, 2014/09/02 17:54:35]

You are completely right.
OnTitleDragCompleted() produces the same bug. I have filed a bug at
http://crbug.com/409888 Will fix in follow up CL

[pkotwicz, 2014/09/02 17:54:35]

I think the comment in ReplaceWindow() is sufficient. Otherwise we would have to
add a comment describing what ReplaceWindow() does at each call site which is
not scalable.

[mfomitchev, 2014/09/02 18:09:46]

Acknowledged.

+        instance->split_view_controller_->left_window(), child);
   } else {
-    size =
+    gfx::Size size =
         gfx::Screen::GetNativeScreen()->GetPrimaryDisplay().work_area().size();
+    child->SetBounds(gfx::Rect(size));
   }
-  child->SetBounds(gfx::Rect(size));
 }
 
 void AthenaContainerLayoutManager::OnWillRemoveWindowFromLayout(