LayerTreeHostImpl knows if it has an output surface.

cc/output/delegating_renderer.h

 // Copyright 2012 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 CC_OUTPUT_DELEGATING_RENDERER_H_
 #define CC_OUTPUT_DELEGATING_RENDERER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/compositor_frame.h"
@@ skipping 19 matching lines @@
                          float device_scale_factor,
                          const gfx::Rect& device_viewport_rect,
                          const gfx::Rect& device_clip_rect,
                          bool disable_picture_quad_image_filtering) OVERRIDE;
 
   virtual void Finish() OVERRIDE {}
 
   virtual void SwapBuffers(const CompositorFrameMetadata& metadata) OVERRIDE;
   virtual void ReceiveSwapBuffersAck(const CompositorFrameAck&) OVERRIDE;
 
-  virtual bool IsContextLost() OVERRIDE;
-
  private:
   DelegatingRenderer(RendererClient* client,
                      const LayerTreeSettings* settings,
                      OutputSurface* output_surface,
                      ResourceProvider* resource_provider);
 
   virtual void DidChangeVisibility() OVERRIDE;
 
   OutputSurface* output_surface_;
   ResourceProvider* resource_provider_;
   RendererCapabilitiesImpl capabilities_;
   scoped_ptr<DelegatedFrameData> delegated_frame_data_;
 
   DISALLOW_COPY_AND_ASSIGN(DelegatingRenderer);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_DELEGATING_RENDERER_H_