[OLD ATTEMPT, DO NOT REVIEW] mustash: Enable connections to mus from the Chrome renderer

content/common/render_process_client.mojom

Index: content/common/render_process_client.mojom
diff --git a/content/common/render_process_client.mojom b/content/common/render_process_client.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..45b52d2f0f01b49fec1ed076184c947f5740b18f
--- /dev/null
+++ b/content/common/render_process_client.mojom
@@ -0,0 +1,12 @@
+// 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.
+
+module content.mojom;
+
+import "components/mus/public/interfaces/window_tree.mojom";
+
+interface RenderProcessClient {
+  OnRenderWidgetViewCreated(uint32 routing_id,
+                            mus.mojom.WindowTreeClient window_tree_client);
+};