Revert of Move DefaultActivationClient to wm/core

ui/aura/test/aura_test_helper.h

Index: ui/aura/test/aura_test_helper.h
diff --git a/ui/aura/test/aura_test_helper.h b/ui/aura/test/aura_test_helper.h
index 05d59abe1fca907f4f1bd1ed60f1277faddcdf2b..f79ca76782c32edbffee0c61fac7b47db93fc5b5 100644
--- a/ui/aura/test/aura_test_helper.h
+++ b/ui/aura/test/aura_test_helper.h
@@ -22,6 +22,7 @@
 namespace aura {
 class TestScreen;
 namespace client {
+class DefaultActivationClient;
 class DefaultCaptureClient;
 class FocusClient;
 }
@@ -59,6 +60,7 @@
   bool owns_host_;
   scoped_ptr<WindowTreeHost> host_;
   scoped_ptr<TestWindowTreeClient> stacking_client_;
+  scoped_ptr<client::DefaultActivationClient> activation_client_;
   scoped_ptr<client::DefaultCaptureClient> capture_client_;
   scoped_ptr<ui::InputMethod> test_input_method_;
   scoped_ptr<client::FocusClient> focus_client_;