Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/spdy_session_key.cc

Index: net/spdy/spdy_session_key.cc
diff --git a/net/spdy/spdy_session_key.cc b/net/spdy/spdy_session_key.cc
index 8b2fcbcc81f879f7e8595d0e986052139f346149..00558e28cb81bc0915edea115803272af79d7362 100644
--- a/net/spdy/spdy_session_key.cc
+++ b/net/spdy/spdy_session_key.cc
@@ -7,6 +7,8 @@
 #include <tuple>
 
 #include "base/logging.h"
+#include "base/trace_event/memory_usage_estimator.h"
+#include "net/base/host_port_pair.h"
 
 namespace net {
 
@@ -49,4 +51,8 @@ bool SpdySessionKey::Equals(const SpdySessionKey& other) const {
       host_port_proxy_pair_.second == other.host_port_proxy_pair_.second;
 }
 
+size_t SpdySessionKey::EstimateMemoryUsage() const {
+  return base::trace_event::EstimateMemoryUsage(host_port_proxy_pair_);
+}
+
 }  // namespace net