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

net/http/http_util.h

Index: net/http/http_util.h
diff --git a/net/http/http_util.h b/net/http/http_util.h
index 1bb3c93f8ab168152dc75205e00aabcc0d9c30cf..d152e62587b469940583499cd33e7733352992f1 100644
--- a/net/http/http_util.h
+++ b/net/http/http_util.h
@@ -80,6 +80,11 @@ class NET_EXPORT HttpUtil {
   // a fully RFC-2616-compliant header value validation.
   static bool IsValidHeaderValue(const std::string& value);
 
+  // Returns true if |value| is a valid HTTP header value according to
+  // RFC 7230 and doesn't contain CR or LF.
+  // i.e. returns true if |value| matches |*field-content| in RFC 7230.
+  static bool IsValidHeaderValueRFC7230(const base::StringPiece& value);
+
   // Strips all header lines from |headers| whose name matches
   // |headers_to_remove|. |headers_to_remove| is a list of null-terminated
   // lower-case header names, with array length |headers_to_remove_len|.