Add a multi-threaded rendering example.

examples/ui/noodles/rasterizer.cc

+// 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.
+
+#include "examples/ui/noodles/rasterizer.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "examples/ui/noodles/frame.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "third_party/skia/include/core/SkSurface.h"
+
+namespace examples {
+
+constexpr uint32_t kContentImageResourceId = 1;
+constexpr uint32_t kRootNodeId = mojo::gfx::composition::kSceneRootNodeId;
+
+Rasterizer::Rasterizer(mojo::ApplicationConnectorPtr connector,
+                       mojo::gfx::composition::ScenePtr scene)
+    : gl_context_owner_(connector.get()),
+      ganesh_context_(gl_context_owner_.context()),
+      ganesh_renderer_(&ganesh_context_),
+      scene_(scene.Pass()) {}
+
+Rasterizer::~Rasterizer() {}
+
+void Rasterizer::PublishFrame(std::unique_ptr<Frame> frame) {
+  DCHECK(frame);
+
+  mojo::Rect bounds;
+  bounds.width = frame->size().width;
+  bounds.height = frame->size().height;
+
+  auto update = mojo::gfx::composition::SceneUpdate::New();
+  mojo::gfx::composition::ResourcePtr content_resource =
+      ganesh_renderer_.DrawCanvas(
+          frame->size(),
+          base::Bind(&Frame::Paint, base::Unretained(frame.get())));
+  DCHECK(content_resource);
+  update->resources.insert(kContentImageResourceId, content_resource.Pass());
+
+  auto root_node = mojo::gfx::composition::Node::New();
+  root_node->op = mojo::gfx::composition::NodeOp::New();
+  root_node->op->set_image(mojo::gfx::composition::ImageNodeOp::New());
+  root_node->op->get_image()->content_rect = bounds.Clone();
+  root_node->op->get_image()->image_resource_id = kContentImageResourceId;
+  update->nodes.insert(kRootNodeId, root_node.Pass());
+
+  scene_->Update(update.Pass());
+  scene_->Publish(frame->TakeSceneMetadata());
+}
+
+}  // namespace examples