Experiment with HSTS preload list filtering.

net/tools/transport_security_state_generator/input_file_parsers.cc

Index: net/tools/transport_security_state_generator/input_file_parsers.cc
diff --git a/net/tools/transport_security_state_generator/input_file_parsers.cc b/net/tools/transport_security_state_generator/input_file_parsers.cc
index 4a633080ed00ec5a830196241985c253babdc411..38c1ac9010f5e6d98b0cc72fd13d348ba49d1262 100644
--- a/net/tools/transport_security_state_generator/input_file_parsers.cc
+++ b/net/tools/transport_security_state_generator/input_file_parsers.cc
@@ -318,6 +318,10 @@ bool ParseJSON(base::StringPiece json,
     parsed->GetString("expect_staple_report_uri",
                       &entry->expect_staple_report_uri);
 
+    int importance = 0;
+    parsed->GetInteger("importance", &importance);
+    entry->importance = static_cast<unsigned>(importance);
+
     entries->push_back(std::move(entry));
   }