Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/hpack/hpack_output_stream.h

 // Copyright 2014 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_SPDY_HPACK_HPACK_OUTPUT_STREAM_H_
 #define NET_SPDY_HPACK_HPACK_OUTPUT_STREAM_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 41 matching lines @@
   // Swaps the internal buffer with |output|, then resets state.
   void TakeString(std::string* output);
 
   // Gives up to |max_size| bytes of the internal buffer to |output|. Resets
   // internal state with the overflow.
   void BoundedTakeString(size_t max_size, std::string* output);
 
   // Size in bytes of stream's internal buffer.
   size_t size() const { return buffer_.size(); }
 
+  // Returns the estimate of dynamically allocated memory in bytes.
+  size_t EstimateMemoryUsage() const;
+
  private:
   // The internal bit buffer.
   std::string buffer_;
 
   // If 0, the buffer ends on a byte boundary. If non-zero, the buffer
   // ends on the nth most significant bit. Guaranteed to be < 8.
   size_t bit_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(HpackOutputStream);
 };
 
 }  // namespace net
 
 #endif  // NET_SPDY_HPACK_HPACK_OUTPUT_STREAM_H_