Add metrics to track HTTP/0.9 usage for main frames and subresources

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 a0143fd8a45ff3a797041e74a2b52108140e0d17..da4e889ca8726ecfa936744c9c0a9c9d8998e17c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -28074,6 +28074,23 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Net.HttpResponseInfo.ConnectionInfo.MainFrame"
+    enum="ConnectionInfo">
+  <owner>mmenke@chromium.org</owner>
+  <summary>
+    Application protocol used in HTTP responses to requests for main frames.
+  </summary>
+</histogram>
+
+<histogram name="Net.HttpResponseInfo.ConnectionInfo.SubResource"
+    enum="ConnectionInfo">
+  <owner>mmenke@chromium.org</owner>
+  <summary>
+    Application protocol used in HTTP responses to requests for resources other
+    than main frames. Does not include internal Chrome requests.
+  </summary>
+</histogram>
+
 <histogram name="Net.HttpServerProperties.UpdatePrefs"
     enum="HttpServerPropertiesUpdatePrefsLocation">
   <owner>rtenneti@chromium.org</owner>
@@ -68535,13 +68552,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     net::HttpResponseInfo::ConnectionInfo.
   </summary>
   <int value="0" label="unknown"/>
-  <int value="1" label="HTTP/0.9, HTTP/1.0, or HTTP/1.1"/>
+  <int value="1" label="HTTP/1.0, or HTTP/1.1"/>
   <int value="2" label="SPDY/2 (deprecated)"/>
   <int value="3" label="SPDY/3"/>
   <int value="4" label="HTTP/2"/>
   <int value="5" label="QUIC"/>
   <int value="6" label="HTTP/2 draft-14"/>
   <int value="7" label="HTTP/2 draft-15"/>
+  <int value="8" label="HTTP/0.9"/>
 </enum>
 
 <enum name="ConnectionResult" type="int">