mus: Add EventObserver to allow passively listening to UI events

components/mus/ws/window_server.cc

 // Copyright 2014 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/ws/window_server.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "components/mus/ws/display.h"
 #include "components/mus/ws/display_binding.h"
@@ skipping 381 matching lines @@
     pair.second->ProcessCursorChanged(window, cursor_id,
                                       IsOperationSource(pair.first));
   }
 
   // Pass the cursor change to the native window.
   Display* display = display_manager_->GetDisplayContaining(window);
   if (display)
     display->OnCursorUpdated(window);
 }
 
+void WindowServer::SendToEventObservers(const ui::Event& event,
+                                        const UserId& user_id,
+                                        WindowTree* ignore_tree) {
+  for (auto& pair : tree_map_) {
+    WindowTree* tree = pair.second.get();
+    if (tree->user_id() == user_id && tree != ignore_tree)
+      tree->SendToEventObserver(event);
+  }
+}
+
 void WindowServer::ProcessViewportMetricsChanged(
     Display* display,
     const mojom::ViewportMetrics& old_metrics,
     const mojom::ViewportMetrics& new_metrics) {
   for (auto& pair : tree_map_) {
     pair.second->ProcessViewportMetricsChanged(
         display, old_metrics, new_metrics, IsOperationSource(pair.first));
   }
 }
 
@@ skipping 234 matching lines @@
 void WindowServer::OnFirstDisplayReady() {
   delegate_->OnFirstDisplayReady();
 }
 
 void WindowServer::OnNoMoreDisplays() {
   delegate_->OnNoMoreDisplays();
 }
 
 }  // namespace ws
 }  // namespace mus