LayerTreeHostImpl knows if it has an output surface.

cc/output/gl_renderer.h

 // Copyright 2010 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_GL_RENDERER_H_
 #define CC_OUTPUT_GL_RENDERER_H_
 
 #include "base/cancelable_callback.h"
 #include "cc/base/cc_export.h"
 #include "cc/base/scoped_ptr_deque.h"
@@ skipping 47 matching lines @@
   virtual ~GLRenderer();
 
   virtual const RendererCapabilitiesImpl& Capabilities() const OVERRIDE;
 
   // Waits for rendering to finish.
   virtual void Finish() OVERRIDE;
 
   virtual void DoNoOp() OVERRIDE;
   virtual void SwapBuffers(const CompositorFrameMetadata& metadata) OVERRIDE;
 
-  virtual bool IsContextLost() OVERRIDE;
+  virtual bool IsContextLost();
 
   static void DebugGLCall(gpu::gles2::GLES2Interface* gl,
                           const char* command,
                           const char* file,
                           int line);
 
  protected:
   GLRenderer(RendererClient* client,
              const LayerTreeSettings* settings,
              OutputSurface* output_surface,
@@ skipping 354 matching lines @@
 #if DEBUG_GL_CALLS && !defined(NDEBUG)
 #define GLC(context, x)                                                        \
   (x, GLRenderer::DebugGLCall(&* context, #x, __FILE__, __LINE__))
 #else
 #define GLC(context, x) (x)
 #endif
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_GL_RENDERER_H_