mus: Add EventObserver to allow passively listening to UI events

components/mus/public/cpp/lib/event_matcher_util.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/event_matcher.h"
+#include "components/mus/public/cpp/event_matcher_util.h"
 
 namespace mus {
 
 mojom::EventMatcherPtr CreateKeyMatcher(mojom::KeyboardCode code, int flags) {
   mojom::EventMatcherPtr matcher(mojom::EventMatcher::New());
   matcher->type_matcher = mojom::EventTypeMatcher::New();
   matcher->flags_matcher = mojom::EventFlagsMatcher::New();
   matcher->ignore_flags_matcher = mojom::EventFlagsMatcher::New();
   // Ignoring these makes most accelerator scenarios more straight forward. Code
   // that needs to check them can override this setting.
   matcher->ignore_flags_matcher->flags = mojom::kEventFlagCapsLockOn |
                                          mojom::kEventFlagScrollLockOn |
                                          mojom::kEventFlagNumLockOn;
   matcher->key_matcher = mojom::KeyEventMatcher::New();
 
   matcher->type_matcher->type = mus::mojom::EventType::KEY_PRESSED;
   matcher->flags_matcher->flags = flags;
   matcher->key_matcher->keyboard_code = code;
   return matcher;
 }
 
 }  // namespace mus