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

net/http/http_util.cc

Index: net/http/http_util.cc
diff --git a/net/http/http_util.cc b/net/http/http_util.cc
index f1e5143e701a5334499dccc9a814ae4c96d2023b..9e30ed60103b790eb43d8bc39f9921b84d9a27ee 100644
--- a/net/http/http_util.cc
+++ b/net/http/http_util.cc
@@ -346,6 +346,32 @@ bool HttpUtil::IsValidHeaderValue(const std::string& value) {
 }
 
 // static
+bool HttpUtil::IsValidHeaderValueRFC7230(const std::string& value) {
+  return IsValidHeaderValueRFC7230(value.begin(), value.end());
+}
+
+// static
+bool HttpUtil::IsValidHeaderValueRFC7230(
+    std::string::const_iterator value_begin,
+    std::string::const_iterator value_end) {
+  // Empty string is a valid header-value.
+  if (value_begin == value_end)
+    return true;
+
+  // Check leading/trailing whitespaces.
+  if (IsLWS(*value_begin) || IsLWS(*(value_end - 1)))
+    return false;
+
+  // Check each octet is |field-vchar|, |SP| or |HTAB|.
+  for (; value_begin != value_end; ++value_begin) {
+    unsigned char c = *value_begin;
+    if (c == 0x7F || c > 0xFF || (c < 0x20 && c != '\t'))
+      return false;
+  }
+  return true;
+}
+
+// static
 std::string HttpUtil::StripHeaders(const std::string& headers,
                                    const char* const headers_to_remove[],
                                    size_t headers_to_remove_len) {