Added notion of currently active app / browser

ui/aura/test/test_activation_client.h

Index: ui/aura/test/test_activation_client.h
diff --git a/ui/aura/test/test_activation_client.h b/ui/aura/test/test_activation_client.h
index 6221d2144ca5f189910cbfe71bc7054e85552300..831cd9c0a8cda5dceec860c5a029a1c8f6bd512c 100644
--- a/ui/aura/test/test_activation_client.h
+++ b/ui/aura/test/test_activation_client.h
@@ -31,11 +31,13 @@ class TestActivationClient : public client::ActivationClient,
   virtual void OnWindowDestroyed(Window* window) OVERRIDE;
 
  private:
+  void RemoveActiveWindow(Window* window);
+
   // This class explicitly does NOT store the active window in a window property
   // to make sure that storing the active window in a property is not treated as
   // part of the aura API. Assumptions to that end will cause tests that use
   // this client to fail.
-  Window* active_window_;
+  std::vector<Window*> active_windows_;
 
   DISALLOW_COPY_AND_ASSIGN(TestActivationClient);
 };