TestScreen shouldn't be marked aura export

ash/wm/base_layout_manager.cc

Index: ash/wm/base_layout_manager.cc
diff --git a/ash/wm/base_layout_manager.cc b/ash/wm/base_layout_manager.cc
index 7fc116de3db541963c866eda3cd79e98f3c8f13c..6a5e5e4697bc12adbbbc03e79777738a49cf090e 100644
--- a/ash/wm/base_layout_manager.cc
+++ b/ash/wm/base_layout_manager.cc
@@ -20,6 +20,7 @@ namespace internal {
 // BaseLayoutManager, public:
 
 BaseLayoutManager::BaseLayoutManager() {
+  Shell::GetInstance()->AddShellObserver(this);
   Shell::GetRootWindow()->AddRootWindowObserver(this);
 }
 
@@ -27,6 +28,7 @@ BaseLayoutManager::~BaseLayoutManager() {
   for (WindowSet::const_iterator i = windows_.begin(); i != windows_.end(); ++i)
     (*i)->RemoveObserver(this);
   Shell::GetRootWindow()->RemoveRootWindowObserver(this);
+  Shell::GetInstance()->RemoveShellObserver(this);
 }
 
 /////////////////////////////////////////////////////////////////////////////
@@ -70,6 +72,9 @@ void BaseLayoutManager::OnRootWindowResized(const gfx::Size& new_size) {
   AdjustWindowSizesForScreenChange();
 }
 
+/////////////////////////////////////////////////////////////////////////////
+// BaseLayoutManager, ash::ShellObserver overrides:
+
 void BaseLayoutManager::OnScreenWorkAreaInsetsChanged() {
   AdjustWindowSizesForScreenChange();
 }