Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/http2_priority_dependencies.cc

Index: net/spdy/http2_priority_dependencies.cc
diff --git a/net/spdy/http2_priority_dependencies.cc b/net/spdy/http2_priority_dependencies.cc
index 9cbfba07c1540cf4a42c39e8575c864e01d17a84..b473164790bdde1cc3d70897c50169bd5920d93f 100644
--- a/net/spdy/http2_priority_dependencies.cc
+++ b/net/spdy/http2_priority_dependencies.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "net/spdy/http2_priority_dependencies.h"
+#include "net/spdy/platform/api/spdy_estimate_memory_usage.h"
 
 namespace net {
 
@@ -157,4 +158,10 @@ void Http2PriorityDependencies::OnStreamDestruction(SpdyStreamId id) {
   entry_by_stream_id_.erase(emit);
 }
 
+size_t Http2PriorityDependencies::EstimateMemoryUsage() const {
+  return SpdyEstimateMemoryUsage(id_priority_lists_);
+  // TODO(xunjieli): https://crbug.com/690015. Include |entry_by_stream_id_|
+  // when memory_usage_estimator.h supports std::list::iterator.
+}
+
 }  // namespace net