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..be79cfc62be04d59d837888944efe49b45a237cb 100644
--- a/net/http/http_util.cc
+++ b/net/http/http_util.cc
@@ -346,6 +346,24 @@ bool HttpUtil::IsValidHeaderValue(const std::string& value) {
 }
 
 // static
+bool HttpUtil::IsValidHeaderValueRFC7230(const base::StringPiece& value) {
+  // This empty string is a valid header-value.
+  if (value.empty())
+    return true;
+
+  // Check leading/trailing whitespaces.
+  if (IsLWS(value[0]) || IsLWS(value[value.size() - 1]))
+    return false;
+
+  // Check each octet is |field-vchar|, |SP| or |HTAB|.
+  for (unsigned char c : value) {
+    if (c == 0x7F || (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) {