Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/http2/hpack/decoder/http2_hpack_decoder.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_HTTP2_HPACK_DECODER_HTTP2_HPACK_DECODER_H_
 #define NET_HTTP2_HPACK_DECODER_HTTP2_HPACK_DECODER_H_
 
 // Decodes HPACK blocks, calls an Http2HpackDecoderListener with the decoded
 // header entries. Also notifies the listener of errors and of the boundaries of
 // the HPACK blocks.
@@ skipping 77 matching lines @@
   bool DecodeFragment(DecodeBuffer* db);
 
   // Completes the process of decoding an HPACK block: if the HPACK block was
   // properly terminated, announces the end of the header list to the listener
   // and returns true; else returns false.
   bool EndDecodingBlock();
 
   // Was an error detected?
   bool error_detected();
 
+  // Returns the estimate of dynamically allocated memory in bytes.
+  size_t EstimateMemoryUsage() const;
+
  private:
   friend class test::Http2HpackDecoderPeer;
 
   // Reports an error to the listener IF this is the first error detected.
   void ReportError(base::StringPiece error_message);
 
   // The decompressor state, as defined by HPACK (i.e. the static and dynamic
   // tables).
   HpackDecoderState decoder_state_;
 
   // Assembles the various parts of a header entry into whole entries.
   HpackWholeEntryBuffer entry_buffer_;
 
   // The decoder of HPACK blocks into entry parts, passed to entry_buffer_.
   HpackBlockDecoder block_decoder_;
 
   // Has an error been detected?
   bool error_detected_;
 
   DISALLOW_COPY_AND_ASSIGN(Http2HpackDecoder);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP2_HPACK_DECODER_HTTP2_HPACK_DECODER_H_