Use active window if on current workspace for fullscreen mode.

ash/root_window_controller.cc

Index: ash/root_window_controller.cc
diff --git a/ash/root_window_controller.cc b/ash/root_window_controller.cc
index a3ec7395f4fbf95b5b91d5360229a98443359f3d..6608e3172ea2e7bb8685d877edeb2dfae095445a 100644
--- a/ash/root_window_controller.cc
+++ b/ash/root_window_controller.cc
@@ -31,6 +31,7 @@
 #include "ash/touch/touch_observer_hud.h"
 #include "ash/wm/always_on_top_controller.h"
 #include "ash/wm/dock/docked_window_layout_manager.h"
+#include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/panels/panel_layout_manager.h"
 #include "ash/wm/panels/panel_window_event_handler.h"
 #include "ash/wm/root_window_layout_manager.h"
@@ -569,18 +570,14 @@ void RootWindowController::UpdateShelfVisibility() {
 }
 
 const aura::Window* RootWindowController::GetWindowForFullscreenMode() const {
-  const aura::Window::Windows& windows =
-      GetContainer(kShellWindowId_DefaultContainer)->children();
   const aura::Window* topmost_window = NULL;
-  for (aura::Window::Windows::const_reverse_iterator iter = windows.rbegin();
-       iter != windows.rend(); ++iter) {
-    if (((*iter)->type() == ui::wm::WINDOW_TYPE_NORMAL ||
-         (*iter)->type() == ui::wm::WINDOW_TYPE_PANEL) &&
-        (*iter)->layer()->GetTargetVisibility()) {
-      topmost_window = *iter;
-      break;
-    }
+  if (Shell::GetInstance()->mru_window_tracker()) {
+    topmost_window = Shell::GetInstance()->mru_window_tracker()->
+        GetMruWindowInRoot(root_window());
   }
+
+  // If any transient parent of the active window is fullscreen the root
+  // window should remain in fullscreen mode.
   while (topmost_window) {
     if (wm::GetWindowState(topmost_window)->IsFullscreen())
       return topmost_window;