Land scaffolding for explicit MDB resource allocation

Change-Id: I1cb30b50068e99181788181683e82e2421d0038a
Reviewed-on: https://skia-review.googlesource.com/46701
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrRenderTargetOpList.h b/src/gpu/GrRenderTargetOpList.h
index 55fc904..cf513b7 100644
--- a/src/gpu/GrRenderTargetOpList.h
+++ b/src/gpu/GrRenderTargetOpList.h
@@ -141,6 +141,8 @@
         GrAppliedClip* fAppliedClip;
     };
 
+    void gatherProxyIntervals(GrResourceAllocator*) const override;
+
     void recordOp(std::unique_ptr<GrOp>, const GrCaps& caps,
                   GrAppliedClip* = nullptr, const DstProxy* = nullptr);