Make mojo renderer capable of supporting multiple streams/tracks

media/mojo/interfaces/renderer.mojom

Index: media/mojo/interfaces/renderer.mojom
diff --git a/media/mojo/interfaces/renderer.mojom b/media/mojo/interfaces/renderer.mojom
index 38ca4401b4b1d429464448095d14ed3ff85e5cc2..0342f0484e10de90a48832ab22dca16c4f6ea9b2 100644
--- a/media/mojo/interfaces/renderer.mojom
+++ b/media/mojo/interfaces/renderer.mojom
@@ -12,11 +12,11 @@ import "ui/gfx/geometry/mojo/geometry.mojom";
 import "url/mojo/url.mojom";
 
 interface Renderer {
-  // Initializes the Renderer with one or both of an audio and video stream,
-  // executing the callback with whether the initialization succeeded.
+  // Initializes the Renderer with either one or more audio / video |streams|,
+  // or a |media_url| executing the callback with whether the initialization
+  // succeeded.
   Initialize(associated RendererClient client,
-             DemuxerStream? audio,
-             DemuxerStream? video,
+             array<DemuxerStream>? streams,
              url.mojom.Url? media_url,
              url.mojom.Url? first_party_for_cookies) => (bool success);