Add a policy to always show the Cast toolbar icon

chrome/browser/profiles/profile_impl.cc

Index: chrome/browser/profiles/profile_impl.cc
diff --git a/chrome/browser/profiles/profile_impl.cc b/chrome/browser/profiles/profile_impl.cc
index 9c4752f9e99322b3d7c62c50f15fe83525a7a52e..445833f8aeda3b98a3670837879eaf1027b65c1f 100644
--- a/chrome/browser/profiles/profile_impl.cc
+++ b/chrome/browser/profiles/profile_impl.cc
@@ -389,7 +389,10 @@ void ProfileImpl::RegisterProfilePrefs(
   registry->RegisterBooleanPref(prefs::kForceEphemeralProfiles, false);
 #if defined(ENABLE_MEDIA_ROUTER)
   registry->RegisterBooleanPref(prefs::kEnableMediaRouter, true);
-#endif
+#if !defined(OS_ANDROID)
+  registry->RegisterBooleanPref(prefs::kShowCastIconInToolbar, false);
+#endif  // !defined(OS_ANDROID)
+#endif  // defined(ENABLE_MEDIA_ROUTER)
   // Initialize the cache prefs.
   registry->RegisterFilePathPref(prefs::kDiskCacheDir, base::FilePath());
   registry->RegisterIntegerPref(prefs::kDiskCacheSize, 0);