mus: Add EventObserver to allow passively listening to UI events

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/mus/public/cpp/tests/test_window_tree.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace mus {
 
@@ skipping 103 matching lines @@
 void TestWindowTree::SetCapture(uint32_t change_id, uint32_t window_id) {
   got_change_ = true;
   change_id_ = change_id;
 }
 
 void TestWindowTree::ReleaseCapture(uint32_t change_id, uint32_t window_id) {
   got_change_ = true;
   change_id_ = change_id;
 }
 
+void TestWindowTree::SetEventObserver(mojom::EventMatcherPtr matcher,
+                                      uint32_t observer_id) {}
+
 void TestWindowTree::Embed(uint32_t window_id,
                            mojom::WindowTreeClientPtr client,
                            const EmbedCallback& callback) {}
 
 void TestWindowTree::SetFocus(uint32_t change_id, uint32_t window_id) {
   got_change_ = true;
   change_id_ = change_id;
 }
 
 void TestWindowTree::SetCanFocus(uint32_t window_id, bool can_focus) {}
@@ skipping 12 matching lines @@
 void TestWindowTree::OnWindowInputEventAck(uint32_t event_id,
                                            mus::mojom::EventResult result) {
   EXPECT_FALSE(acked_events_.count(event_id));
   acked_events_.insert(event_id);
 }
 
 void TestWindowTree::GetWindowManagerClient(
     mojo::AssociatedInterfaceRequest<mojom::WindowManagerClient> internal) {}
 
 }  // namespace mus