Ignore fullscreen windows which are behind other windows for fullscreen mode.

ash/wm/overview/window_selector_controller.cc

Index: ash/wm/overview/window_selector_controller.cc
diff --git a/ash/wm/overview/window_selector_controller.cc b/ash/wm/overview/window_selector_controller.cc
index a148357669c2265ef22e60a3533548bcdf9440e1..fcbb9ae7b85403e5bbba41e0c077922cf9869f1c 100644
--- a/ash/wm/overview/window_selector_controller.cc
+++ b/ash/wm/overview/window_selector_controller.cc
@@ -72,18 +72,6 @@ bool WindowSelectorController::IsSelecting() {
 
 void WindowSelectorController::OnWindowSelected(aura::Window* window) {
   window_selector_.reset();
-
-  // If there is a fullscreen window on this display and it was not selected
-  // it should exit fullscreen mode.
-  internal::RootWindowController* controller =
-      internal::GetRootWindowController(window->GetRootWindow());
-  aura::Window* fullscreen_window = NULL;
-  if (controller)
-    fullscreen_window = controller->GetTopmostFullscreenWindow();
-  if (fullscreen_window && fullscreen_window != window) {
-    wm::GetWindowState(fullscreen_window)->ToggleFullscreen();
-  }
-
   wm::ActivateWindow(window);
   last_selection_time_ = base::Time::Now();
   Shell::GetInstance()->mru_window_tracker()->SetIgnoreActivations(false);