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

services/ui/surfaces/direct_output_surface_ozone.h

Index: services/ui/surfaces/direct_output_surface_ozone.h
diff --git a/services/ui/surfaces/direct_output_surface_ozone.h b/services/ui/surfaces/direct_output_surface_ozone.h
index 603bd356e1510b4fb95905043a7e7034ac67c297..c585f1a5ff27a825ca762b9921a5499fd086b287 100644
--- a/services/ui/surfaces/direct_output_surface_ozone.h
+++ b/services/ui/surfaces/direct_output_surface_ozone.h
@@ -53,7 +53,7 @@ class DirectOutputSurfaceOzone : public cc::OutputSurface {
 
  private:
   // cc::OutputSurface implementation.
-  bool BindToClient(cc::OutputSurfaceClient* client) override;
+  void BindToClient(cc::OutputSurfaceClient* client) override;
   void EnsureBackbuffer() override;
   void DiscardBackbuffer() override;
   void BindFramebuffer() override;
@@ -77,6 +77,8 @@ class DirectOutputSurfaceOzone : public cc::OutputSurface {
   // Called when a swap completion is sent from the GPU process.
   void OnGpuSwapBuffersCompleted(gfx::SwapResult result);
 
+  cc::OutputSurfaceClient* client_ = nullptr;
+
   display_compositor::GLHelper gl_helper_;
   std::unique_ptr<display_compositor::BufferQueue> buffer_queue_;
   cc::SyntheticBeginFrameSource* const synthetic_begin_frame_source_;