mus: Add PointerWatcher for passively observing mouse and touch events

ui/views/mus/window_manager_connection.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 UI_VIEWS_MUS_WINDOW_MANAGER_CONNECTION_H_
 #define UI_VIEWS_MUS_WINDOW_MANAGER_CONNECTION_H_
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "components/mus/public/cpp/window_tree_delegate.h"
 #include "services/shell/public/cpp/identity.h"
 #include "ui/views/mus/mus_export.h"
 #include "ui/views/mus/screen_mus_delegate.h"
 #include "ui/views/widget/widget.h"
 
 namespace shell {
 class Connector;
 }
 
 namespace views {
 class NativeWidget;
+class PointerWatcher;
 class ScreenMus;
 namespace internal {
 class NativeWidgetDelegate;
 }
 
 // Provides configuration to mus in views. This consists of the following:
 // . Provides a Screen implementation backed by mus.
 // . Creates and owns a WindowTreeConnection.
 // . Registers itself as the factory for creating NativeWidgets so that a
 //   NativeWidgetMus is created.
@@ skipping 15 matching lines @@
   shell::Connector* connector() { return connector_; }
 
   mus::Window* NewWindow(const std::map<std::string,
                          std::vector<uint8_t>>& properties);
 
   NativeWidget* CreateNativeWidgetMus(
       const std::map<std::string, std::vector<uint8_t>>& properties,
       const Widget::InitParams& init_params,
       internal::NativeWidgetDelegate* delegate);
 
+  void AddPointerWatcher(PointerWatcher* watcher);
+  void RemovePointerWatcher(PointerWatcher* watcher);
+
  private:
+  friend class WindowManagerConnectionTest;
+
   WindowManagerConnection(shell::Connector* connector,
                           const shell::Identity& identity);
   ~WindowManagerConnection() override;
 
+  // Returns true if there is one or more pointer watchers for this client.
+  bool HasPointerWatcher();
+
   // mus::WindowTreeDelegate:
   void OnEmbed(mus::Window* root) override;
   void OnConnectionLost(mus::WindowTreeConnection* connection) override;
+  void OnEventObserved(const ui::Event& event) override;
 
   // ScreenMusDelegate:
   void OnWindowManagerFrameValuesChanged() override;
 
   shell::Connector* connector_;
   shell::Identity identity_;
   std::unique_ptr<ScreenMus> screen_;
   std::unique_ptr<mus::WindowTreeConnection> window_tree_connection_;
+  // Must be empty on destruction.
+  base::ObserverList<PointerWatcher, true> pointer_watchers_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowManagerConnection);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_MUS_WINDOW_MANAGER_CONNECTION_H_