Add UMAs for checking header values against RFC 7230 in //net

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 24ab831396d14877b353128bd9c668c6a8abdd1b..cb355eb435cdbb4cb73747bdba4a74024a066884 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -24165,6 +24165,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Net.HttpRequestContainsInvalidHeaderValuesInRFC7230"
+    enum="Boolean">
+  <owner>hiroshige@chromium.org</owner>
+  <summary>
+    Whether a request contains invalid request header values in RFC 7230.
+    https://crbug.com/455099.

[davidben, 2015/12/15 21:16:36]

Probably should add "this is counted once for every redirect leg" or something
of the sort.

[hiroshige, 2015/12/17 06:36:02]

Done.

+  </summary>
+</histogram>
+
 <histogram name="Net.HttpResponseCode">
   <owner>mmenke@chromium.org</owner>
   <summary>The count of HTTP Response codes encountered.</summary>
@@ -24178,6 +24187,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Net.HttpResponseContainsInvalidHeaderValuesInRFC7230"
+    enum="Boolean">
+  <owner>hiroshige@chromium.org</owner>
+  <summary>
+    Whether a response contains invalid response header values in RFC 7230.
+    https://crbug.com/455099.

[davidben, 2015/12/15 21:16:36]

Ditto.

[hiroshige, 2015/12/17 06:36:02]

Done.

+  </summary>
+</histogram>
+
 <histogram name="Net.HttpResponseInfo.ConnectionInfo" enum="ConnectionInfo">
   <owner>bnc@chromium.org</owner>
   <summary>