Revert "Revert "drm_hwcomposer: have DrmDisplayCompositor do its own OpenGL composition""

This reverts commit cbe9c01336e23a63259db65d22d63d6a697b8813.
diff --git a/glworker.h b/glworker.h
index e9febec..9550cbe 100644
--- a/glworker.h
+++ b/glworker.h
@@ -88,6 +88,8 @@
 
   int Composite(hwc_layer_1 *layers, size_t num_layers,
                 sp<GraphicBuffer> framebuffer);
+  int CompositeAndFinish(hwc_layer_1 *layers, size_t num_layers,
+                         sp<GraphicBuffer> framebuffer);
 
  private:
   EGLDisplay egl_display_;