gpu: Empty swaps for surfaceless output surfaces.

components/display_compositor/buffer_queue.h

Index: components/display_compositor/buffer_queue.h
diff --git a/components/display_compositor/buffer_queue.h b/components/display_compositor/buffer_queue.h
index 7ac212e1be72b2dbcfbc20828e0d22f2c5834c56..c6bedbb1757ff8cc06f73889f3d34d3acbd087f9 100644
--- a/components/display_compositor/buffer_queue.h
+++ b/components/display_compositor/buffer_queue.h
@@ -60,12 +60,9 @@ class DISPLAY_COMPOSITOR_EXPORT BufferQueue {
                float scale_factor,
                const gfx::ColorSpace& color_space,
                bool use_stencil);
-
   void RecreateBuffers();
+  uint32_t GetCurrentTextureId() const;
 
-  uint32_t current_texture_id() const {
-    return current_surface_ ? current_surface_->texture : 0;
-  }
   uint32_t fbo() const { return fbo_; }
   uint32_t internal_format() const { return internal_format_; }