Fix offscreen rendering on iOS by not assuming that the default window bound framebuffer is 0

sky/shell/gpu/rasterizer.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_RASTERIZER_H_
 #define SKY_SHELL_GPU_RASTERIZER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "skia/ext/refptr.h"
@@ skipping 20 matching lines @@
   ~Rasterizer();
 
   base::WeakPtr<Rasterizer> GetWeakPtr();
 
   void OnAcceleratedWidgetAvailable(gfx::AcceleratedWidget widget) override;
   void OnOutputSurfaceDestroyed() override;
   void Draw(skia::RefPtr<SkPicture> picture) override;
 
  private:
   void EnsureGLContext();
-  void EnsureGaneshSurface(const gfx::Size& size);
+  void EnsureGaneshSurface(intptr_t window_fbo, const gfx::Size& size);
   void DrawPicture(SkPicture* picture);
 
   scoped_refptr<gfx::GLShareGroup> share_group_;
   scoped_refptr<gfx::GLSurface> surface_;
   scoped_refptr<gfx::GLContext> context_;
 
   scoped_ptr<GaneshContext> ganesh_context_;
   scoped_ptr<GaneshSurface> ganesh_surface_;
 
   base::WeakPtrFactory<Rasterizer> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Rasterizer);
 };
 
 }  // namespace shell
 }  // namespace sky
 
 #endif  // SKY_SHELL_GPU_RASTERIZER_H_