Add a simple compositor for Sky

sky/compositor/layer.cc

+// Copyright 2014 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 "sky/compositor/layer.h"
+
+#include "mojo/skia/ganesh_surface.h"
+#include "sky/compositor/layer_host.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+
+namespace sky {
+
+Layer::Layer(LayerClient* client) : client_(client), host_(nullptr) {
+}
+
+Layer::~Layer() {
+}
+
+void Layer::ClearClient() {
+  client_ = nullptr;
+}
+
+void Layer::SetSize(const gfx::Size& size) {
+  size_ = size;
+}
+
+void Layer::Display() {
+  DCHECK(host_);
+
+  mojo::GaneshContext::Scope scope(host_->ganesh_context());
+  mojo::GaneshSurface surface(host_->ganesh_context(),
+                              host_->resource_manager()->CreateTexture(size_));
+
+  SkCanvas* canvas = surface.canvas();
+
+  gfx::Rect rect(size_);
+  client_->PaintContents(canvas, rect);
+  canvas->flush();
+
+  texture_ = surface.TakeTexture();
+}
+
+scoped_ptr<mojo::GLTexture> Layer::GetTexture() {
+  return texture_.Pass();
+}
+
+}  // namespace sky