Add mus_demo mojo app.

components/mus/demo/mus_demo.h

Index: components/mus/demo/mus_demo.h
diff --git a/components/mus/demo/mus_demo.h b/components/mus/demo/mus_demo.h
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index 0000000000000000000000000000000000000000..0f1056a0ee43a67de50fe825c4bd05ac046cdda9
--- /dev/null
+++ b/components/mus/demo/mus_demo.h
@@ -0,0 +1,91 @@
+// Copyright 2016 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 COMPONENTS_MUS_DEMO_MUS_DEMO_H_
+#define COMPONENTS_MUS_DEMO_MUS_DEMO_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/timer/timer.h"
+#include "components/mus/public/cpp/window.h"
+#include "components/mus/public/cpp/window_manager_delegate.h"
+#include "components/mus/public/cpp/window_tree_delegate.h"
+#include "components/mus/public/interfaces/window_tree_host.mojom.h"
+#include "mojo/public/cpp/bindings/binding_set.h"
+#include "mojo/shell/public/cpp/connector.h"
+#include "mojo/shell/public/cpp/shell_client.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+
+namespace bitmap_uploader {
+class BitmapUploader;
+}
+
+namespace mus {

[rjkroege, 2016/03/29 18:53:23]

I think it would be better to be in a different name space.

[kylechar, 2016/03/29 20:43:39]

Done.

+
+// A simple MUS Demo mojo app. This app connects to the mojo:mus, creates a new
+// window and draws a spinning square in the center of the window. Provides a
+// simple way to demonstrate the graphic stack works as intended.

[rjkroege, 2016/03/29 18:53:22]

to demonstrate that the 

[kylechar, 2016/03/29 20:43:39]

Done.

+class MusDemo : public mojo::ShellClient,
+                public WindowTreeDelegate,
+                public WindowManagerDelegate {
+ public:
+  MusDemo();
+  ~MusDemo() override;
+
+ private:
+  // mojo::ShellClient:
+  void Initialize(mojo::Connector* connector,
+                  const mojo::Identity& identity,
+                  uint32_t id) override;
+  bool AcceptConnection(mojo::Connection* connection) override;
+
+  // WindowTreeDelegate:
+  void OnEmbed(Window* root) override;
+  void OnUnembed(Window* root) override;
+  void OnConnectionLost(WindowTreeConnection* connection) override;
+
+  // WindowManagerDelegate:
+  void SetWindowManagerClient(WindowManagerClient* client) override;
+  bool OnWmSetBounds(Window* window, gfx::Rect* bounds) override;
+  bool OnWmSetProperty(Window* window,
+                       const std::string& name,
+                       scoped_ptr<std::vector<uint8_t>>* new_data) override;
+  Window* OnWmCreateTopLevelWindow(
+      std::map<std::string, std::vector<uint8_t>>* properties) override;
+  void OnAccelerator(uint32_t id, const ui::Event& event) override;
+
+  // Allocate a bitmap the same size as the window t draw into.

[rjkroege, 2016/03/29 18:53:23]

t -> to

[kylechar, 2016/03/29 20:43:39]

Done.

+  void AllocBitmap();
+
+  // Draws one frame, incrementing the rotation angle.
+  void DrawFrame();
+
+  mojo::Connector* connector_ = nullptr;

[rjkroege, 2016/03/29 18:53:23]

These are owned elsewhere? if so, adding // NOT OWNED is conventional

If they are not owned elsewhere, how are they managed?

[kylechar, 2016/03/29 20:43:39]

I believe they're owned elsewhere (based on other code that uses mus::Window and
Mojo::Connector).

Devils advocate: It wouldn't be a raw pointer if it was owned? I realize older
part of the chrome codebase might not use smart pointers yet but for newer code
it can probably be assumed? If you feel strongly I'll add a comment.

[rjkroege, 2016/03/29 20:56:54]

My understanding is that the mojo owns infrastructure owns it.

+
+  mojom::WindowTreeHostPtr host_ = nullptr;
+
+  Window* window_ = nullptr;
+
+  // Used to send frames to mus.
+  scoped_ptr<bitmap_uploader::BitmapUploader> uploader_;
+
+  // Bitmap that is the same size as our client window area.
+  SkBitmap bitmap_;
+
+  // Timer for calling DrawFrame().
+  base::RepeatingTimer timer_;
+
+  // Current rotation angle for drawing.
+  double angle_ = 0.0;
+
+  DISALLOW_COPY_AND_ASSIGN(MusDemo);
+};
+
+}  // namespace mus
+#endif  // COMPONENTS_MUS_DEMO_MUS_DEMO_H_