chromeos: makes mus send keyevents to display root when nothing has focus

services/ui/ws/window_manager_display_root.h

Index: services/ui/ws/window_manager_display_root.h
diff --git a/services/ui/ws/window_manager_display_root.h b/services/ui/ws/window_manager_display_root.h
index 1eacb3a9568ecab1389b7e43bc890b6151b8ca59..d08dcecca4d2559ce62b2d816eb12f2779276270 100644
--- a/services/ui/ws/window_manager_display_root.h
+++ b/services/ui/ws/window_manager_display_root.h
@@ -28,9 +28,23 @@ class WindowManagerDisplayRoot {
   explicit WindowManagerDisplayRoot(Display* display);
   ~WindowManagerDisplayRoot();
 
+  // NOTE: this window is not necessarily visible to the window manager. When
+  // the display roots are automatically created this root is visible to the
+  // window manager. When the display roots are not automatically created this
+  // root has a single child that is created by the client. Use
+  // GetClientVisibileRoot() to get the root that is visible to the client.
   ServerWindow* root() { return root_.get(); }
   const ServerWindow* root() const { return root_.get(); }
 
+  // See root() for details of this. This returns null until the client creates
+  // the root.
+  ServerWindow* GetClientVisibileRoot() {
+    return const_cast<ServerWindow*>(
+        const_cast<const WindowManagerDisplayRoot*>(this)
+            ->GetClientVisibileRoot());
+  }
+  const ServerWindow* GetClientVisibileRoot() const;
+
   Display* display() { return display_; }
   const Display* display() const { return display_; }