Teach SkyShell how to draw with Ganesh

sky/shell/gpu/ganesh_context.h

Index: sky/shell/gpu/ganesh_context.h
diff --git a/sky/shell/gpu/ganesh_context.h b/sky/shell/gpu/ganesh_context.h
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+// 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_CONTEXT_H_
+#define SKY_SHELL_GPU_GANESH_CONTEXT_H_
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "skia/ext/refptr.h"
+#include "third_party/skia/include/gpu/GrContext.h"
+#include "ui/gl/gl_context.h"
+
+namespace sky {
+namespace shell {
+
+// GaneshContext holds the top-level context object for Ganesh (known as
+// GrContext). We construct the GrContext using the OpenGL interface provided by
+// gfx::GLContext.
+class GaneshContext {
+ public:
+  explicit GaneshContext(scoped_refptr<gfx::GLContext> gl_context);
+  ~GaneshContext();
+
+  GrContext* gr() const { return gr_context_.get(); }
+
+ private:
+  scoped_refptr<gfx::GLContext> gl_context_;
+  skia::RefPtr<GrContext> gr_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(GaneshContext);
+};
+
+}  // namespace shell
+}  // namespace sky
+
+#endif  // SKY_SHELL_GPU_GANESH_CONTEXT_H_