Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/hpack/hpack_decoder.cc

Index: net/spdy/hpack/hpack_decoder.cc
diff --git a/net/spdy/hpack/hpack_decoder.cc b/net/spdy/hpack/hpack_decoder.cc
index 575a5c19b715a25d0989b9048e808b137da3231c..27827b94c7a979ebc626775a80a8484b9f8110af 100644
--- a/net/spdy/hpack/hpack_decoder.cc
+++ b/net/spdy/hpack/hpack_decoder.cc
@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "base/logging.h"
+#include "base/trace_event/memory_usage_estimator.h"
 #include "net/spdy/hpack/hpack_constants.h"
 #include "net/spdy/hpack/hpack_entry.h"
 #include "net/spdy/spdy_flags.h"
@@ -116,6 +117,14 @@ void HpackDecoder::set_max_decode_buffer_size_bytes(
   max_decode_buffer_size_bytes_ = max_decode_buffer_size_bytes;
 }
 
+size_t HpackDecoder::EstimateMemoryUsage() const {
+  return header_table_.size() +
+         base::trace_event::EstimateMemoryUsage(headers_block_buffer_) +
+         base::trace_event::EstimateMemoryUsage(decoded_block_) +
+         base::trace_event::EstimateMemoryUsage(key_buffer_) +
+         base::trace_event::EstimateMemoryUsage(value_buffer_);
+}
+
 bool HpackDecoder::HandleHeaderRepresentation(StringPiece name,
                                               StringPiece value) {
   size_updates_allowed_ = false;