mus: Add watcher for all touch events.

ui/views/touch_event_watcher.h

Index: ui/views/touch_event_watcher.h
diff --git a/ui/views/touch_event_watcher.h b/ui/views/touch_event_watcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..d9fb2931732a9a427edbb70284eea874e210851d
--- /dev/null
+++ b/ui/views/touch_event_watcher.h
@@ -0,0 +1,38 @@
+// Copyright 2016 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 UI_VIEWS_TOUCH_EVENT_WATCHER_H_
+#define UI_VIEWS_TOUCH_EVENT_WATCHER_H_
+
+#include "ui/views/views_export.h"
+
+namespace gfx {
+class Point;
+}
+
+namespace ui {
+class LocatedEvent;
+}
+
+namespace views {
+class Widget;
+
+// An interface for read-only observation of touch events (in particular, the
+// events cannot be marked as handled). Only touch pointer kind are supported.
+// The |target| is the top-level widget that will receive the event, if any.
+// NOTE: On mus this allows observation of events outside of windows owned
+// by the current process, in which case the |target| will be null. On mus
+// event.target() is always null.
+class VIEWS_EXPORT TouchEventWatcher {
+ public:
+  virtual void OnTouchEventObserved(const ui::LocatedEvent& event,
+                                    Widget* target) = 0;
+
+ protected:
+  virtual ~TouchEventWatcher() {}
+};

[msw, 2016/07/12 22:23:11]

nit: private: DISALLOW_COPY_AND_ASSIGN?

[riajiang, 2016/07/13 15:40:21]

Done.

+
+}  // namespace views
+
+#endif  // UI_VIEWS_TOUCH_EVENT_WATCHER_H_