Changes how window manager obtains WindowTree from mus

components/mus/ws/window_tree_binding.h

Index: components/mus/ws/window_tree_binding.h
diff --git a/components/mus/ws/window_tree_binding.h b/components/mus/ws/window_tree_binding.h
index 729a8b15a3b67aaa7beefa20c1a758d0972d6267..a9472b3566c5bf9321759e284431686ef9aeb889 100644
--- a/components/mus/ws/window_tree_binding.h
+++ b/components/mus/ws/window_tree_binding.h
@@ -17,9 +17,10 @@ namespace ws {
 class WindowServer;
 class WindowTree;
 
-// WindowTreeBinding manages the binding between a WindowTree and its mojo
-// clients. WindowTreeBinding exists so that the client can be mocked for
-// tests. WindowTree owns its associated WindowTreeBinding.
+// WindowTreeBinding manages the binding between a WindowTree and its
+// WindowTreeClient. WindowTreeBinding exists so that a mock implementation
+// of WindowTreeClient can be injected for tests. WindowTree owns its
+// associated WindowTreeBinding.
 class WindowTreeBinding {
  public:
   explicit WindowTreeBinding(mojom::WindowTreeClient* client);