The function PresentationReceiverWindowEnabled() in media_router_feature.h indicates whether Create() can be called on WiredDisplayPresentationReceiverFactory to generate a WiredDisplayPresentationReceiver.  It exists because the window is currently only implemented with Views and so it only works on Mac when mac_views_browser=1; this is not the default.  Cocoa is expected to be removed from Chromium soon enough that there is no plan to implement the window with Cocoa.  When Mac Views is launched and becomes the default on Mac, PresentationReceiverWindowEnabled() should be removed.