Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/hpack/hpack_decoder2.cc

Index: net/spdy/hpack/hpack_decoder2.cc
diff --git a/net/spdy/hpack/hpack_decoder2.cc b/net/spdy/hpack/hpack_decoder2.cc
index 03b1c2ef229415eb0322a972f1a5cbc40b96d1ae..ebaf51b2715a701369e86336f490b710d3aefa73 100644
--- a/net/spdy/hpack/hpack_decoder2.cc
+++ b/net/spdy/hpack/hpack_decoder2.cc
@@ -9,6 +9,7 @@
 
 #include "base/logging.h"
 #include "base/strings/string_piece.h"
+#include "base/trace_event/memory_usage_estimator.h"
 #include "net/http2/decoder/decode_buffer.h"
 #include "net/http2/decoder/decode_status.h"
 #include "net/spdy/hpack/hpack_entry.h"
@@ -159,6 +160,12 @@ void HpackDecoder2::set_max_decode_buffer_size_bytes(
   max_decode_buffer_size_bytes_ = max_decode_buffer_size_bytes;
 }
 
+size_t HpackDecoder2::EstimateMemoryUsage() const {
+  return header_table_.size() +
+         base::trace_event::EstimateMemoryUsage(decoded_block_) +
+         name_.BufferedLength() + value_.BufferedLength();
+}
+
 void HpackDecoder2::OnIndexedHeader(size_t index) {
   DVLOG(2) << "HpackDecoder2::OnIndexedHeader: index=" << index;
   DCHECK(!error_detected_);