Extracts parameters to WindowTreeHostMus into structure

ui/aura/mus/window_tree_host_mus_init_params.cc

Index: ui/aura/mus/window_tree_host_mus_init_params.cc
diff --git a/ui/aura/mus/window_tree_host_mus_init_params.cc b/ui/aura/mus/window_tree_host_mus_init_params.cc
new file mode 100644
index 0000000000000000000000000000000000000000..10daf0f18b9d348fcfd822f25ca4267675da3942
--- /dev/null
+++ b/ui/aura/mus/window_tree_host_mus_init_params.cc
@@ -0,0 +1,38 @@
+// Copyright 2017 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 "ui/aura/mus/window_tree_host_mus_init_params.h"
+
+#include "ui/aura/mus/window_port_mus.h"
+#include "ui/aura/mus/window_tree_client.h"
+#include "ui/display/display.h"
+#include "ui/display/screen.h"
+
+namespace aura {
+
+WindowTreeHostMusInitParams::WindowTreeHostMusInitParams() = default;
+
+WindowTreeHostMusInitParams::WindowTreeHostMusInitParams(
+    WindowTreeHostMusInitParams&& other) = default;
+
+WindowTreeHostMusInitParams::~WindowTreeHostMusInitParams() = default;
+
+WindowTreeHostMusInitParams CreateInitParamsForTopLevel(
+    WindowTreeClient* window_tree_client,
+    std::map<std::string, std::vector<uint8_t>> properties) {
+  WindowTreeHostMusInitParams params;
+  params.window_tree_client = window_tree_client;
+  params.display_id = display::Screen::GetScreen()->GetPrimaryDisplay().id();
+  // Pass |properties| to CreateWindowPortForTopLevel() so that |properties|
+  // are passed to the server *and* pass |properties| to the WindowTreeHostMus
+  // constructor (above) which applies the properties to the Window. Some of the
+  // properties may be server specific and not applied to the Window.
+  params.window_port =
+      static_cast<WindowTreeHostMusDelegate*>(window_tree_client)
+          ->CreateWindowPortForTopLevel(&properties);
+  params.properties = std::move(properties);
+  return params;
+}
+
+}  // namespace aura