Expose Deleter in Context Pool

Summary: As title.

Reviewed By: yfeldblum

Differential Revision: D17937014

fbshipit-source-id: a0ff5f5f9cbbb182794dc564610d7adb9c7c8d08

folly/compression/CompressionContextPool.h

@@ -64,17 +64,21 @@ class CompressionContextPool {
       if (t == nullptr) {
         throw_exception<std::bad_alloc>();
       }
-      return Ref(t, ReturnToPoolDeleter(this, deleter_));
+      return Ref(t, get_deleter());
     }
     auto ptr = std::move(stack->back());
     stack->pop_back();
-    return Ref(ptr.release(), ReturnToPoolDeleter(this, deleter_));
+    return Ref(ptr.release(), get_deleter());
   }
 
   size_t size() {
     return stack_.rlock()->size();
   }
 
+  ReturnToPoolDeleter get_deleter() {
+    return ReturnToPoolDeleter(this, deleter_);
+  }
+
  private:
   void add(InternalRef ptr) {
     DCHECK(ptr);