Allow creating opaque swapchains in DirectCompositionSurfaceWin

gpu/ipc/service/direct_composition_surface_win.h

Index: gpu/ipc/service/direct_composition_surface_win.h
diff --git a/gpu/ipc/service/direct_composition_surface_win.h b/gpu/ipc/service/direct_composition_surface_win.h
index 22917e766259641937e01aeeefee92078f6ef641..d6e8315ba4e93d24b943ea2c2f2ecd796264d40b 100644
--- a/gpu/ipc/service/direct_composition_surface_win.h
+++ b/gpu/ipc/service/direct_composition_surface_win.h
@@ -96,6 +96,7 @@ class GPU_EXPORT DirectCompositionSurfaceWin : public gl::GLSurfaceEGL {
   gfx::Size size_ = gfx::Size(1, 1);
   bool first_swap_ = true;
   bool enable_dc_layers_ = false;
+  bool has_alpha_ = true;
   std::unique_ptr<gfx::VSyncProvider> vsync_provider_;
   gfx::Rect swap_rect_;
   std::unique_ptr<DCLayerTree> layer_tree_;