Implement Token Binding negotiation TLS extension

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 9ec692d7f0b42f988c624c9005b5038139735cc2..a08606e17433ec54256ad3342257b51c774add4a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -46570,6 +46570,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Number of retries until the final response was recorded.</summary>
 </histogram>
 
+<histogram name="TokenBinding.Support" enum="TokenBinding.Support">
+  <owner>nharper@chromium.org</owner>
+  <summary>
+    Counts of SSL client sockets broken down by support for the Token Binding
+    TLS extension. Counts only connections with full handshakes; resumed
+    sessions are not counted.
+  </summary>
+</histogram>
+
 <histogram name="Toolbar.ActionsModel.ComponentActionsCount">
   <owner>rdevlin.cronin@chromium.org</owner>
   <summary>
@@ -72471,6 +72480,19 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="1" label="Renegotiation patched"/>
 </enum>
 
+<enum name="TokenBinding.Support" type="int">
+  <int value="0" label="DISABLED"/>
+  <int value="1" label="CLIENT_ONLY"/>
+  <int value="2" label="CLIENT_AND_SERVER"/>
+  <int value="3" label="CLIENT_NO_ECC">
+    Token Binding was enabled, but the client does not support ECC key
+    generation.
+  </int>
+  <int value="4" label="CLIENT_NO_CHANNEL_ID_SERVICE">
+    The SSLClientSocket was created without a ChannelIDService.
+  </int>
+</enum>
+
 <enum name="TouchEventsState" type="int">
   <int value="0" label="Enabled"/>
   <int value="1" label="Automatic - enabled"/>