cc: Make OutputSurface::BindToClient pure virtual and not return bool

services/ui/surfaces/direct_output_surface.h

 // Copyright 2014 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 SERVICES_UI_SURFACES_DIRECT_OUTPUT_SURFACE_H_
 #define SERVICES_UI_SURFACES_DIRECT_OUTPUT_SURFACE_H_
 
 #include <memory>
 
 #include "cc/output/output_surface.h"
@@ skipping 11 matching lines @@
 // swaps to an actual GL surface.
 class DirectOutputSurface : public cc::OutputSurface,
                             public SurfacesContextProviderDelegate {
  public:
   explicit DirectOutputSurface(
       scoped_refptr<SurfacesContextProvider> context_provider,
       cc::SyntheticBeginFrameSource* synthetic_begin_frame_source);
   ~DirectOutputSurface() override;
 
   // cc::OutputSurface implementation
-  bool BindToClient(cc::OutputSurfaceClient* client) override;
+  void BindToClient(cc::OutputSurfaceClient* client) override;
   void EnsureBackbuffer() override;
   void DiscardBackbuffer() override;
   void BindFramebuffer() override;
   void Reshape(const gfx::Size& size,
                float device_scale_factor,
                const gfx::ColorSpace& color_space,
                bool has_alpha) override;
   void SwapBuffers(cc::OutputSurfaceFrame frame) override;
   uint32_t GetFramebufferCopyTextureFormat() override;
   cc::OverlayCandidateValidator* GetOverlayCandidateValidator() const override;
   bool IsDisplayedAsOverlayPlane() const override;
   unsigned GetOverlayTextureId() const override;
   bool SurfaceIsSuspendForRecycle() const override;
   bool HasExternalStencilTest() const override;
   void ApplyExternalStencil() override;
 
   // SurfacesContextProviderDelegate implementation
   void OnVSyncParametersUpdated(const base::TimeTicks& timebase,
                                 const base::TimeDelta& interval) override;
 
  private:
   void OnSwapBuffersComplete();
 
+  cc::OutputSurfaceClient* client_ = nullptr;
   cc::SyntheticBeginFrameSource* const synthetic_begin_frame_source_;
   base::WeakPtrFactory<DirectOutputSurface> weak_ptr_factory_;
 };
 
 }  // namespace ui
 
 #endif  // SERVICES_UI_SURFACES_DIRECT_OUTPUT_SURFACE_H_