mus: The window server needs to be able to write to the clipboard.

services/ui/ws/window_server.h

Index: services/ui/ws/window_server.h
diff --git a/services/ui/ws/window_server.h b/services/ui/ws/window_server.h
index 89780988a41c557ccc4671f6609d7a6f1d282dc2..1ff4e3b448e2e1906e200fe5c23b2df7e67a9270 100644
--- a/services/ui/ws/window_server.h
+++ b/services/ui/ws/window_server.h
@@ -15,6 +15,7 @@
 #include "base/macros.h"
 #include "mojo/public/cpp/bindings/array.h"
 #include "mojo/public/cpp/bindings/binding.h"
+#include "services/ui/clipboard/clipboard_impl.h"
 #include "services/ui/public/interfaces/window_manager_window_tree_factory.mojom.h"
 #include "services/ui/public/interfaces/window_tree.mojom.h"
 #include "services/ui/public/interfaces/window_tree_host.mojom.h"
@@ -131,6 +132,8 @@ class WindowServer : public ServerWindowDelegate,
 
   void OnFirstWindowManagerWindowTreeFactoryReady();
 
+  clipboard::ClipboardImpl* GetClipboardForUser(const UserId& user_id);
+
   UserActivityMonitor* GetUserActivityMonitorForUser(const UserId& user_id);
 
   WindowManagerWindowTreeFactorySet* window_manager_window_tree_factory_set() {
@@ -218,6 +221,8 @@ class WindowServer : public ServerWindowDelegate,
       std::map<ClientSpecificId, std::unique_ptr<WindowTree>>;
   using UserActivityMonitorMap =
       std::map<UserId, std::unique_ptr<UserActivityMonitor>>;
+  using UserClipboardMap =
+      std::map<UserId, std::unique_ptr<ui::clipboard::ClipboardImpl>>;
 
   struct InFlightWindowManagerChange {
     // Identifies the client that initiated the change.
@@ -350,6 +355,7 @@ class WindowServer : public ServerWindowDelegate,
   base::Callback<void(ServerWindow*)> window_paint_callback_;
 
   UserActivityMonitorMap activity_monitor_map_;
+  UserClipboardMap clipboard_map_;
 
   WindowManagerWindowTreeFactorySet window_manager_window_tree_factory_set_;