Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/hpack/hpack_huffman_table.h

Index: net/spdy/hpack/hpack_huffman_table.h
diff --git a/net/spdy/hpack/hpack_huffman_table.h b/net/spdy/hpack/hpack_huffman_table.h
index 96c39504dbdd0ee30028b8c5bd2b40b2c776a4e4..386e2aaaa3e60166dcda4cf13802203fe098a012 100644
--- a/net/spdy/hpack/hpack_huffman_table.h
+++ b/net/spdy/hpack/hpack_huffman_table.h
@@ -94,6 +94,9 @@ class NET_EXPORT_PRIVATE HpackHuffmanTable {
   bool GenericDecodeString(HpackInputStream* in,
                            std::string* out) const;
 
+  // Returns the estimate of dynamically allocated memory in bytes.
+  size_t EstimateMemoryUsage() const;
+
  private:
   // Expects symbols ordered on length & ID ascending.
   void BuildDecodeTables(const std::vector<Symbol>& symbols);