Extracts parameters to WindowTreeHostMus into structure

ui/aura/mus/window_tree_host_mus_init_params.h

Index: ui/aura/mus/window_tree_host_mus_init_params.h
diff --git a/ui/aura/mus/window_tree_host_mus_init_params.h b/ui/aura/mus/window_tree_host_mus_init_params.h
new file mode 100644
index 0000000000000000000000000000000000000000..9836b3a75242390bc4e3d6e1f5dd6a53cb279d59
--- /dev/null
+++ b/ui/aura/mus/window_tree_host_mus_init_params.h
@@ -0,0 +1,54 @@
+// 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.
+
+#ifndef UI_AURA_MUS_WINDOW_TREE_HOST_MUS_INIT_PARAMS_H_
+#define UI_AURA_MUS_WINDOW_TREE_HOST_MUS_INIT_PARAMS_H_
+
+#include <stdint.h>
+
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "cc/surfaces/frame_sink_id.h"
+#include "ui/aura/aura_export.h"
+
+namespace aura {
+
+class WindowPortMus;
+class WindowTreeClient;
+
+// Used to create a WindowTreeHostMus. The typical case is to use
+// CreateInitParamsForTopLevel().
+struct AURA_EXPORT WindowTreeHostMusInitParams {
+  WindowTreeHostMusInitParams();
+  ~WindowTreeHostMusInitParams();
+
+  // The WindowTreeClient; must be specified.
+  WindowTreeClient* window_tree_client = nullptr;
+
+  // Used to create the Window; must be specified.
+  std::unique_ptr<WindowPortMus> window_port;
+
+  // Properties to send to the server as well as to set on the Window.
+  std::map<std::string, std::vector<uint8_t>> properties;
+
+  cc::FrameSinkId frame_sink_id;
+
+  // Id of the display the window should be created on.
+  int64_t display_id = 0;
+};
+
+// Creates a WindowTreeHostMusInitParams that is used when creating a top-level
+// window.
+AURA_EXPORT std::unique_ptr<WindowTreeHostMusInitParams>

[Elliot Glaysher, 2017/04/19 17:17:33]

Is there a reason you're using a unique_ptr instead of making
WindowTreeHostMusInitParams movable? You don't appear to be doing any subtyping
of the struct.

+CreateInitParamsForTopLevel(
+    WindowTreeClient* window_tree_client,
+    std::map<std::string, std::vector<uint8_t>> properties =
+        std::map<std::string, std::vector<uint8_t>>());
+
+}  // namespace aura
+
+#endif  // UI_AURA_MUS_WINDOW_TREE_HOST_MUS_INIT_PARAMS_H_