Add a command-line switch to disable the media router

This is useful for local development, because the media router opens up
a local port and that triggers a permission dialog on macOS.

Bug: 1111418
Change-Id: I9da8167d77615bce7840ff82723260a951671eb7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2330007Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Takumi Fujimoto <takumif@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795252}

chrome/browser/media/router/media_router_feature.cc

@@ -30,6 +30,13 @@
 namespace media_router {
 
 #if !defined(OS_ANDROID)
+#if !defined(OFFICIAL_BUILD)
+// Enables the media router. Can be useful to disable for local
+// development on Mac because DIAL local discovery opens a local port
+// and triggers a permission prompt. Only toggleable for developer builds.
+const base::Feature kMediaRouter{"MediaRouter",
+                                 base::FEATURE_ENABLED_BY_DEFAULT};
+#endif  // !defined(OFFICIAL_BUILD)
 // Controls if browser side DialMediaRouteProvider is enabled.
 const base::Feature kDialMediaRouteProvider{"DialMediaRouteProvider",
                                             base::FEATURE_ENABLED_BY_DEFAULT};
@@ -39,7 +46,7 @@ const base::Feature kCastAllowAllIPsFeature{"CastAllowAllIPs",
                                             base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kGlobalMediaControlsCastStartStop{
     "GlobalMediaControlsCastStartStop", base::FEATURE_DISABLED_BY_DEFAULT};
-#endif
+#endif  // !defined(OS_ANDROID)
 
 #if defined(OS_ANDROID) || BUILDFLAG(ENABLE_EXTENSIONS)
 namespace {
@@ -52,6 +59,11 @@ const PrefService::Preference* GetMediaRouterPref(
 #endif  // defined(OS_ANDROID) || BUILDFLAG(ENABLE_EXTENSIONS)
 
 bool MediaRouterEnabled(content::BrowserContext* context) {
+#if !defined(OFFICIAL_BUILD) && !defined(OS_ANDROID)
+  if (!base::FeatureList::IsEnabled(kMediaRouter))
+    return false;
+#endif  // !defined(OFFICIAL_BUILD) && !defined(OS_ANDROID)
+
 #if defined(OS_ANDROID) || BUILDFLAG(ENABLE_EXTENSIONS)
   const PrefService::Preference* pref = GetMediaRouterPref(context);
   // Only use the pref value if it set from a mandatory policy.