Reland Mus Demo: Move definition of WindowTreeData into separate files

services/ui/demo/window_tree_data.h

Index: services/ui/demo/window_tree_data.h
diff --git a/services/ui/demo/window_tree_data.h b/services/ui/demo/window_tree_data.h
new file mode 100644
index 0000000000000000000000000000000000000000..0e1bcbd0806f8cc96f1feb5cdaf4c26a18b5d571
--- /dev/null
+++ b/services/ui/demo/window_tree_data.h
@@ -0,0 +1,60 @@
+// 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 SERVICES_UI_DEMO_WINDOW_TREE_DATA_H_
+#define SERVICES_UI_DEMO_WINDOW_TREE_DATA_H_
+
+#include "base/memory/ptr_util.h"
+#include "base/timer/timer.h"
+
+namespace aura {
+class Window;
+class WindowTreeHostMus;
+}  // namespace aura
+
+namespace aura_extra {
+class ImageWindowDelegate;
+}  // namespace aura_extra
+
+namespace ui {
+namespace demo {
+
+class WindowTreeData {
+ public:
+  explicit WindowTreeData(int square_size);
+  ~WindowTreeData();
+
+  // Initializes the window tree host and start drawing frames.
+  void Init(std::unique_ptr<aura::WindowTreeHostMus> window_tree_host);
+  bool IsInitialized() const { return !!window_tree_host_; }
+
+ private:
+  // Draws one frame, incrementing the rotation angle.
+  void DrawFrame();
+
+  // Helper function to retrieve the window to which we draw the bitmap.
+  aura::Window* bitmap_window();
+
+  // The Window tree host corresponding to this data.
+  std::unique_ptr<aura::WindowTreeHostMus> window_tree_host_;
+
+  // Destroys itself when the window gets destroyed.
+  aura_extra::ImageWindowDelegate* window_delegate_ = nullptr;
+
+  // Timer for calling DrawFrame().
+  base::RepeatingTimer timer_;
+
+  // Current rotation angle for drawing.
+  double angle_ = 0.0;
+
+  // Size in pixels of the square to draw.
+  const int square_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowTreeData);
+};
+
+}  // namespace demo
+}  // namespace ui
+
+#endif  // SERVICES_UI_DEMO_WINDOW_TREE_DATA_H_