[Media Router] Convert to use typemaps for media_router.mojom.

chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/media_router/media_router_webui_message_handler.h"
 
 #include <string>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 80 matching lines @@
 
   std::unique_ptr<base::ListValue> sinks_val(new base::ListValue);
 
   for (const MediaSinkWithCastModes& sink_with_cast_modes : sinks) {
     std::unique_ptr<base::DictionaryValue> sink_val(new base::DictionaryValue);
 
     const MediaSink& sink = sink_with_cast_modes.sink;
     sink_val->SetString("id", sink.id());
     sink_val->SetString("name", sink.name());
     sink_val->SetInteger("iconType", sink.icon_type());
-    if (!sink.description().empty())
-      sink_val->SetString("description", sink.description());
+    if (sink.description())
+      sink_val->SetString("description", *sink.description());
 
     bool is_pseudo_sink =
         base::StartsWith(sink.id(), "pseudo:", base::CompareCase::SENSITIVE);
-    if (!user_domain.empty() && !sink.domain().empty()) {
-      std::string domain = sink.domain();
+    if (!user_domain.empty() && sink.domain() && !sink.domain()->empty()) {
+      std::string domain = *sink.domain();
       // Convert default domains to user domain
-      if (sink.domain() == "default") {
+      if (domain == "default") {
         domain = user_domain;
         if (domain == Profile::kNoHostedDomainFound) {
           // Default domain will be empty for non-dasher accounts.
           domain.clear();
         }
       }
 
       sink_val->SetString("domain", domain);
 
       show_email = show_email || !is_pseudo_sink;
@@ skipping 776 matching lines @@
   }
 
   return value;
 }
 
 void MediaRouterWebUIMessageHandler::SetWebUIForTest(content::WebUI* web_ui) {
   set_web_ui(web_ui);
 }
 
 }  // namespace media_router