Fix WebSocketServer extension parser.

net/websockets/websocket_extension.cc

Index: net/websockets/websocket_extension.cc
diff --git a/net/websockets/websocket_extension.cc b/net/websockets/websocket_extension.cc
index bf7a54bdbf3e17b79f4da23476525ea19d11a39e..f1e6a24090ccf8831125ba916f043ec7780365f5 100644
--- a/net/websockets/websocket_extension.cc
+++ b/net/websockets/websocket_extension.cc
@@ -45,4 +45,35 @@ bool WebSocketExtension::Equals(const WebSocketExtension& other) const {
   return this_parameters == other_parameters;
 }
 
+std::string WebSocketExtension::ToString() const {
+  if (name_.empty()) {
+    return std::string();
+  }
+
+  std::string result = name_;
+
+  for (const auto& param : parameters_) {
+    result += "; " + param.name();
+    if (!param.HasValue())
+      continue;
+
+    result += "=";
+    const auto& value = param.value();
+    if (value.find('"') == std::string::npos) {
+      result += value;
+    } else {
+      result += '"';
+      for (const auto& c : value) {
+        if (c == '"') {
+          result += "\\\"";
+        } else {
+          result += c;
+        }
+      }
+      result += '"';
+    }
+  }
+  return result;
+}
+
 }  // namespace net