[chrome.displaySource] Move video stream info creation to encoders.

extensions/renderer/api/display_source/wifi_display/wifi_display_media_encoder.h

Index: extensions/renderer/api/display_source/wifi_display/wifi_display_media_encoder.h
diff --git a/extensions/renderer/api/display_source/wifi_display/wifi_display_media_encoder.h b/extensions/renderer/api/display_source/wifi_display/wifi_display_media_encoder.h
index 788f3e6641c6e48b80f0c81e9e5e6f38c3cdbfbd..d205719a31019732e9735290b0afb55fc7511222 100644
--- a/extensions/renderer/api/display_source/wifi_display/wifi_display_media_encoder.h
+++ b/extensions/renderer/api/display_source/wifi_display/wifi_display_media_encoder.h
@@ -14,6 +14,7 @@
 #include "base/move.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_checker.h"
+#include "extensions/renderer/api/display_source/wifi_display/wifi_display_elementary_stream_info.h"
 
 namespace extensions {
 
@@ -51,6 +52,13 @@ class WiFiDisplayMediaEncoder
   using EncodedUnitCallback =
       base::Callback<void(std::unique_ptr<WiFiDisplayEncodedUnit>)>;
 
+  // Creates an elementary stream info describing the stream of encoded units
+  // which this encoder generates and passes to a callback set using
+  // |SetCallbacks|. The created elementary stream info should be passed to
+  // a Wi-Fi Display media packetizer.
+  virtual WiFiDisplayElementaryStreamInfo CreateElementaryStreamInfo()
+      const = 0;
+
   // Sets callbacks for the obtained encoder instance:
   // |encoded_callback| is invoked to return the next encoded unit
   // |error_callback| is invoked to report a fatal encoder error