Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/spdy_session_key.h

Index: net/spdy/spdy_session_key.h
diff --git a/net/spdy/spdy_session_key.h b/net/spdy/spdy_session_key.h
index 31d61a3e8afb389c8dcfd2958e3b6e9c5768c814..f6a823803a970138d58931e5b5a09270e0cbf04c 100644
--- a/net/spdy/spdy_session_key.h
+++ b/net/spdy/spdy_session_key.h
@@ -49,6 +49,9 @@ class NET_EXPORT_PRIVATE SpdySessionKey {
     return privacy_mode_;
   }
 
+  // Returns the estimate of dynamically allocated memory in bytes.
+  size_t EstimateMemoryUsage() const;
+
  private:
   HostPortProxyPair host_port_proxy_pair_;
   // If enabled, then session cannot be tracked by the server.