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

net/http/http_request_headers.cc

Index: net/http/http_request_headers.cc
diff --git a/net/http/http_request_headers.cc b/net/http/http_request_headers.cc
index c2eee59af95f8408a9d11ad774986e302270175b..fa1c99d16a74241a56f5d9592cbaf829ad1ae61a 100644
--- a/net/http/http_request_headers.cc
+++ b/net/http/http_request_headers.cc
@@ -5,6 +5,7 @@
 #include "net/http/http_request_headers.h"
 
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ -86,6 +87,8 @@ void HttpRequestHeaders::SetHeader(const base::StringPiece& key,
                                    const base::StringPiece& value) {
   DCHECK(HttpUtil::IsValidHeaderName(key.as_string()));
   DCHECK(HttpUtil::IsValidHeaderValue(value.as_string()));
+  UMA_HISTOGRAM_BOOLEAN("Net.HttpRequestHeaderValueValidInRFC7230",
+                        HttpUtil::IsValidHeaderValueRFC7230(value));
   HeaderVector::iterator it = FindHeader(key);
   if (it != headers_.end())
     it->value.assign(value.data(), value.size());
@@ -97,6 +100,8 @@ void HttpRequestHeaders::SetHeaderIfMissing(const base::StringPiece& key,
                                             const base::StringPiece& value) {
   DCHECK(HttpUtil::IsValidHeaderName(key.as_string()));
   DCHECK(HttpUtil::IsValidHeaderValue(value.as_string()));
+  UMA_HISTOGRAM_BOOLEAN("Net.HttpRequestHeaderValueValidInRFC7230",
+                        HttpUtil::IsValidHeaderValueRFC7230(value));
   HeaderVector::iterator it = FindHeader(key);
   if (it == headers_.end())
     headers_.push_back(HeaderKeyValuePair(key, value));