views/mus: Add a test to verify that Widget receives events correctly.

components/mus/public/cpp/tests/window_tree_client_impl_private.cc

Index: components/mus/public/cpp/tests/window_tree_client_impl_private.cc
diff --git a/components/mus/public/cpp/tests/window_tree_client_impl_private.cc b/components/mus/public/cpp/tests/window_tree_client_impl_private.cc
index 795e3dc0d2020322c46105298d64e2af29c53425..28f6b0ff101afe87268f8698efd8ba77792f890f 100644
--- a/components/mus/public/cpp/tests/window_tree_client_impl_private.cc
+++ b/components/mus/public/cpp/tests/window_tree_client_impl_private.cc
@@ -5,7 +5,9 @@
 #include "components/mus/public/cpp/tests/window_tree_client_impl_private.h"
 
 #include "components/mus/public/cpp/lib/window_tree_client_impl.h"
+#include "components/mus/public/cpp/window.h"
 #include "mojo/converters/geometry/geometry_type_converters.h"
+#include "mojo/converters/input_events/input_events_type_converters.h"
 
 namespace mus {
 
@@ -13,6 +15,9 @@ WindowTreeClientImplPrivate::WindowTreeClientImplPrivate(
     WindowTreeClientImpl* tree_client_impl)
     : tree_client_impl_(tree_client_impl) {}
 
+WindowTreeClientImplPrivate::WindowTreeClientImplPrivate(Window* window)
+    : WindowTreeClientImplPrivate(window->tree_client()) {}
+
 WindowTreeClientImplPrivate::~WindowTreeClientImplPrivate() {}
 
 uint32_t WindowTreeClientImplPrivate::event_observer_id() {
@@ -33,4 +38,13 @@ void WindowTreeClientImplPrivate::OnEmbed(mojom::WindowTree* window_tree) {
   tree_client_impl_->OnEmbedImpl(window_tree, 1, std::move(root_data), 0, true);
 }
 
+void WindowTreeClientImplPrivate::CallOnWindowInputEvent(
+    Window* window,
+    const ui::Event& event) {
+  const uint32_t event_id = 0u;
+  const uint32_t observer_id = 0u;
+  tree_client_impl_->OnWindowInputEvent(event_id, window->server_id(),
+                                        mojom::Event::From(event), observer_id);
+}
+
 }  // namespace mus