QUIC - Persist 1000 MRU alternate protocols to preferences file.

net/http/http_server_properties.cc

Index: net/http/http_server_properties.cc
diff --git a/net/http/http_server_properties.cc b/net/http/http_server_properties.cc
index 72b47c1b349819da4efd848f0c0f0ce3804c3191..19b334c1fb3b737820c0d8aef1cc56a99f566815 100644
--- a/net/http/http_server_properties.cc
+++ b/net/http/http_server_properties.cc
@@ -31,9 +31,20 @@ COMPILE_ASSERT(
 
 }  // namespace
 
-void HistogramAlternateProtocolUsage(AlternateProtocolUsage usage) {
+void HistogramAlternateProtocolUsage(
+    AlternateProtocolUsage usage,
+    AlternateProtocolExperiment alternate_protocol_experiment) {
   UMA_HISTOGRAM_ENUMERATION("Net.AlternateProtocolUsage", usage,
                             ALTERNATE_PROTOCOL_USAGE_MAX);
+  if (alternate_protocol_experiment ==
+      ALTERNATE_PROTOCOL_TRUNCATED_200_SERVERS) {
+    UMA_HISTOGRAM_ENUMERATION("Net.AlternateProtocolUsage.200Truncated", usage,
+                              ALTERNATE_PROTOCOL_USAGE_MAX);
+  } else if (alternate_protocol_experiment ==
+      ALTERNATE_PROTOCOL_TRUNCATED_1000_SERVERS) {
+    UMA_HISTOGRAM_ENUMERATION("Net.AlternateProtocolUsage.1000Truncated", usage,
+                              ALTERNATE_PROTOCOL_USAGE_MAX);
+  }
 }
 
 void HistogramBrokenAlternateProtocolLocation(