Replace SSLProtocolNegotiation histogram with SSLNegotiatedAlpnProtocol.

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 acd066011acf3affe6c1b09c97b61041d8ab2ed0..650dc71d30a185394e7ac77d7906d19ca7c3e678 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -32563,6 +32563,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Net.SSLProtocolNegotiation" enum="SSLProtocolNegotiation">
+  <obsolete>
+    Superseded by SSL.AlpnNegotiatedProtocol in 2016 August.
+  </obsolete>
   <owner>bnc@chromium.org</owner>
   <summary>
     TLS extension used to negotiate protocol (ALPN or NPN); in case of NPN,
@@ -57137,6 +57140,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SSL.AlpnNegotiatedProtocol" enum="AlpnNegotiatedProtocol">
+  <owner>bnc@chromium.org</owner>
+  <summary>
+    For each TLS handshake, whether ALPN was negotiated; and if so, the
+    negotiated protocol.
+  </summary>
+</histogram>
+
 <histogram name="SSL.CertificateErrorReportFailure" enum="NetErrorCodes">
   <owner>estark@chromium.org</owner>
   <summary>
@@ -68275,6 +68286,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="2" label="Malformed response"/>
 </enum>
 
+<enum name="AlpnNegotiatedProtocol" type="int">
+  <int value="0" label="ALPN not used"/>
+  <int value="1" label="HTTP/1.1 negotiated via ALPN"/>
+  <int value="2" label="HTTP/2 negotiated via ALPN"/>
+</enum>
+
 <enum name="AlternateProtocolUsage" type="int">
   <int value="0" label="ALTERNATE_PROTOCOL_USAGE_NO_RACE"/>
   <int value="1" label="ALTERNATE_PROTOCOL_USAGE_WON_RACE"/>