[Media Router] Conditionally enable mDNS on Windows.

chrome/browser/ui/webui/media_router/media_router_ui.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_ui.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
 #include "base/guid.h"
 #include "base/i18n/string_compare.h"
 #include "base/macros.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/trace_event/trace_event.h"
+#include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/media/router/create_presentation_connection_request.h"
 #include "chrome/browser/media/router/issue.h"
 #include "chrome/browser/media/router/issues_observer.h"
 #include "chrome/browser/media/router/media_route.h"
 #include "chrome/browser/media/router/media_router.h"
 #include "chrome/browser/media/router/media_router_factory.h"
 #include "chrome/browser/media/router/media_router_metrics.h"
 #include "chrome/browser/media/router/media_router_mojo_impl.h"
 #include "chrome/browser/media/router/media_routes_observer.h"
@@ skipping 216 matching lines @@
   OnDefaultPresentationChanged(create_session_request_->presentation_request());
 }
 
 void MediaRouterUI::InitCommon(content::WebContents* initiator) {
   DCHECK(initiator);
   DCHECK(router_);
 
   TRACE_EVENT_NESTABLE_ASYNC_INSTANT1("media_router", "UI", initiator,
                                       "MediaRouterUI::InitCommon", this);
 
+#if defined(OS_WIN)
+  if (!router_->should_enable_mdns_discovery()) {

[mark a. foltz, 2016/03/24 22:59:33]

IMO, this is confusing to read.

One solution:

1. The router could keep track of whether EnableMdnsDiscovery has already been
called on the MRPM by adding an internal flag
2. The method below is renamed to EnsureMdnsDiscoveryEnabled() (no-op if the
flag in #1 is true)
3. Just call EnsureMdnsDiscoveryEnabled() here.


 

[btolsch, 2016/03/25 04:40:50]

I thought about putting a comment here since that if reads pretty badly, but I
like this better.

+    router_->EnableMdnsDiscovery();
+  }
+#endif
   // Create |collator_| before |query_result_manager_| so that |collator_| is
   // already set up when we get a callback from |query_result_manager_|.
   UErrorCode error = U_ZERO_ERROR;
   const std::string& locale = g_browser_process->GetApplicationLocale();
   collator_.reset(
       icu::Collator::createInstance(icu::Locale(locale.c_str()), error));
   if (U_FAILURE(error)) {
     DLOG(ERROR) << "Failed to create collator for locale " << locale;
     collator_.reset();
   }
@@ skipping 314 matching lines @@
         base::Time::Now() - start_time_);
     start_time_ = base::Time();
   }
 }
 
 void MediaRouterUI::UpdateMaxDialogHeight(int height) {
   handler_->UpdateMaxDialogHeight(height);
 }
 
 }  // namespace media_router