Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/proxy/proxy_server.cc

Index: net/proxy/proxy_server.cc
diff --git a/net/proxy/proxy_server.cc b/net/proxy/proxy_server.cc
index 76fa0d6224f346fe45f7eacf9c45c255b5252e1d..ed81ebbb26b4f439d618c115b32f49249d9284a6 100644
--- a/net/proxy/proxy_server.cc
+++ b/net/proxy/proxy_server.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include "base/strings/string_util.h"
+#include "base/trace_event/memory_usage_estimator.h"
 #include "net/base/url_util.h"
 #include "net/http/http_util.h"
 
@@ -209,6 +210,10 @@ ProxyServer::Scheme ProxyServer::GetSchemeFromURI(const std::string& scheme) {
   return GetSchemeFromURIInternal(scheme);
 }
 
+size_t ProxyServer::EstimateMemoryUsage() const {
+  return base::trace_event::EstimateMemoryUsage(host_port_pair_);
+}
+
 // static
 ProxyServer ProxyServer::FromSchemeHostAndPort(
     Scheme scheme,