WebLayer: enable Remote Playback and Presentation APIs.

Without this change, only media-fling works. Even with these flags
removed, the APIs are still disabled for clients that don't explicitly
enable Media Router functionality.

Bug: 1057099, 1057100
Change-Id: I7f63dd36798a499011ddd722ebeb682532f7ddda
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2486455
Auto-Submit: Evan Stade <estade@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818996}

weblayer/app/content_main_delegate_impl.cc

@@ -144,10 +144,6 @@ bool ContentMainDelegateImpl::BasicStartupComplete(int* exit_code) {
   // TODO(crbug.com/1025610): make notifications work with WebLayer.
   // This also turns off Push messaging.
   cl->AppendSwitch(::switches::kDisableNotifications);
-  // TODO(crbug.com/1057099): make presentation-api work with WebLayer.
-  cl->AppendSwitch(::switches::kDisablePresentationAPI);
-  // TODO(crbug.com/1057100): make remote-playback-api work with WebLayer.
-  cl->AppendSwitch(::switches::kDisableRemotePlaybackAPI);
 
   std::vector<base::Feature> enabled_features = {};
   std::vector<base::Feature> disabled_features = {