mus: Add EventObserver to allow passively listening to UI events

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

 // 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.
 
 #ifndef COMPONENTS_MUS_PUBLIC_CPP_TESTS_TEST_WINDOW_TREE_H_
 #define COMPONENTS_MUS_PUBLIC_CPP_TESTS_TEST_WINDOW_TREE_H_
 
 #include <stdint.h>
 
 #include <set>
@@ skipping 59 matching lines @@
                                        uint32_t window_id) override;
   void SetModal(uint32_t change_id, uint32_t window_id) override;
   void ReorderWindow(uint32_t change_id,
                      uint32_t window_id,
                      uint32_t relative_window_id,
                      mojom::OrderDirection direction) override;
   void GetWindowTree(uint32_t window_id,
                      const GetWindowTreeCallback& callback) override;
   void SetCapture(uint32_t change_id, uint32_t window_id) override;
   void ReleaseCapture(uint32_t change_id, uint32_t window_id) override;
+  void SetEventObserver(mojom::EventMatcherPtr matcher,
+                        uint32_t observer_id) override;
   void Embed(uint32_t window_id,
              mojom::WindowTreeClientPtr client,
              const EmbedCallback& callback) override;
   void SetFocus(uint32_t change_id, uint32_t window_id) override;
   void SetCanFocus(uint32_t window_id, bool can_focus) override;
   void SetPredefinedCursor(uint32_t change_id,
                            uint32_t window_id,
                            mus::mojom::Cursor cursor_id) override;
   void SetWindowTextInputState(uint32_t window_id,
                                mojo::TextInputStatePtr state) override;
@@ skipping 10 matching lines @@
   uint32_t change_id_;
   std::set<uint32_t> acked_events_;
   uint32_t window_id_;
 
   DISALLOW_COPY_AND_ASSIGN(TestWindowTree);
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_TESTS_TEST_WINDOW_TREE_H_