Overlays: Remove special casing of primary overlay plane

cc/test/fake_output_surface.h

Index: cc/test/fake_output_surface.h
diff --git a/cc/test/fake_output_surface.h b/cc/test/fake_output_surface.h
index d2af2e3d44c7400bf163e7dba965318379b9a862..1f2c2f84aefcddce6d463557667d9791d19d5d81 100644
--- a/cc/test/fake_output_surface.h
+++ b/cc/test/fake_output_surface.h
@@ -123,6 +123,8 @@ class FakeOutputSurface : public OutputSurface {
 
   bool SurfaceIsSuspendForRecycle() const override;
 
+  unsigned GetOverlayTextureId() const override;
+
   void set_has_external_stencil_test(bool has_test) {
     has_external_stencil_test_ = has_test;
   }