Make ui::test::EventGenerator work with PointerEvents in mash

ui/aura/test/event_generator_delegate_aura.cc

Index: ui/aura/test/event_generator_delegate_aura.cc
diff --git a/ui/aura/test/event_generator_delegate_aura.cc b/ui/aura/test/event_generator_delegate_aura.cc
index 59d3de3bc5432f38ca00f795d38ebf39e2afba04..25a7e141061b8c3c497d11909b51d124f1bca78f 100644
--- a/ui/aura/test/event_generator_delegate_aura.cc
+++ b/ui/aura/test/event_generator_delegate_aura.cc
@@ -7,6 +7,9 @@
 #include "base/macros.h"
 #include "base/memory/singleton.h"
 #include "ui/aura/client/screen_position_client.h"
+#include "ui/aura/env.h"
+#include "ui/aura/test/env_test_helper.h"
+#include "ui/aura/test/mus/window_tree_client_private.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/ime/input_method.h"
@@ -136,5 +139,21 @@ void EventGeneratorDelegateAura::DispatchKeyEventToIME(ui::EventTarget* target,
   window->GetHost()->GetInputMethod()->DispatchKeyEvent(event);
 }
 
+void EventGeneratorDelegateAura::DispatchEventToPointerWatchers(
+    ui::EventTarget* target,
+    const ui::PointerEvent& event) {
+  // In non-mus aura PointerWatchers are handled by system-wide EventHandlers,
+  // for example ash::Shell and ash::PointerWatcherAdapter.
+  if (!Env::GetInstance()->HasWindowTreeClient())
+    return;
+
+  // Route the event through WindowTreeClient as in production mus. Does nothing
+  // if there are no PointerWatchers installed.
+  Window* window = static_cast<Window*>(target);
+  WindowTreeClient* window_tree_client = EnvTestHelper().GetWindowTreeClient();
+  WindowTreeClientPrivate(window_tree_client)
+      .CallOnPointerEventObserved(window, ui::Event::Clone(event));
+}
+
 }  // namespace test
 }  // namespace aura