Teach SkyShell how to draw with Ganesh

sky/shell/gpu/ganesh_surface.h

+// 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.
+
+#ifndef SKY_SHELL_GPU_GANESH_SURFACE_H_
+#define SKY_SHELL_GPU_GANESH_SURFACE_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "skia/ext/refptr.h"
+#include "sky/shell/gpu/ganesh_context.h"
+#include "third_party/skia/include/core/SkSurface.h"
+#include "ui/gfx/geometry/size.h"
+
+namespace sky {
+namespace shell {
+
+// GaneshSurface holds an SkSurface configured to render with Ganesh. Using the
+// provided GaneshContext, GaneshSurface wraps an SkSurface around FBO 0 so that
+// you can use |canvas()| to draw to FBO 0.
+class GaneshSurface {
+ public:
+  GaneshSurface(GaneshContext* context, const gfx::Size& size);
+  ~GaneshSurface();
+
+  SkCanvas* canvas() const { return surface_->getCanvas(); }
+  gfx::Size size() const {
+    return gfx::Size(surface_->width(), surface_->height());
+  }
+
+ private:
+  skia::RefPtr<SkSurface> surface_;
+
+  DISALLOW_COPY_AND_ASSIGN(GaneshSurface);
+};
+
+}  // namespace shell
+}  // namespace sky
+
+#endif  // SKY_SHELL_GPU_GANESH_SURFACE_H_