Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/spdy_write_queue.cc

Index: net/spdy/spdy_write_queue.cc
diff --git a/net/spdy/spdy_write_queue.cc b/net/spdy/spdy_write_queue.cc
index 50df9440a777541ffcf4cbc66c45eb4f08243a02..26427185dd8be0e5ac22ed91f58312c030c0d95a 100644
--- a/net/spdy/spdy_write_queue.cc
+++ b/net/spdy/spdy_write_queue.cc
@@ -155,4 +155,10 @@ void SpdyWriteQueue::Clear() {
   removing_writes_ = false;
 }
 
+size_t SpdyWriteQueue::EstimateMemoryUsage() const {
+  // TODO(xunjieli): https://crbug.com/669108. return allocation from |queue_|
+  // once memory_usage_estimator.h supports std::deque.
+  return 0;
+}
+
 }  // namespace net