[Presentation API] (1st) (1-UA) Add is_offscreen_presentation attribute to MediaRouter

chrome/browser/media/router/mojo/media_router.mojom

Index: chrome/browser/media/router/mojo/media_router.mojom
diff --git a/chrome/browser/media/router/mojo/media_router.mojom b/chrome/browser/media/router/mojo/media_router.mojom
index e68a1e09f020fc35b6330550ea6cf52d1d67fcf8..aa960d6e856b8b19137b82184e5ea234459dd1c7 100644
--- a/chrome/browser/media/router/mojo/media_router.mojom
+++ b/chrome/browser/media/router/mojo/media_router.mojom
@@ -50,6 +50,8 @@ struct MediaRoute {
   bool for_display;
   // Set to true if this route was created by an incognito profile.
   bool is_incognito;
+  // Set to true if this route corresponds to an offscreen presentation.
+  bool is_offscreen_presentation;
 };
 
 // Notifications or an actionable events to be shown to the user.