[chrome.displaySource] Implement hardware accelerated H.264 video encoder.

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

Index: extensions/renderer/api/display_source/wifi_display/wifi_display_video_encoder.h
diff --git a/extensions/renderer/api/display_source/wifi_display/wifi_display_video_encoder.h b/extensions/renderer/api/display_source/wifi_display/wifi_display_video_encoder.h
index ec17ef69b7582c39d09b8859092ae475916c1962..d992d4742f9ce0c668d638519f7e85ad9a6e520c 100644
--- a/extensions/renderer/api/display_source/wifi_display/wifi_display_video_encoder.h
+++ b/extensions/renderer/api/display_source/wifi_display/wifi_display_video_encoder.h
@@ -43,7 +43,7 @@ class WiFiDisplayVideoEncoder : public WiFiDisplayMediaEncoder {
     int bit_rate;
     wds::H264Profile profile;
     wds::H264Level level;
-    // VEA-specific parameters.
+    // Video Encode Accelerator (VEA) specific parameters.
     CreateEncodeMemoryCallback create_memory_callback;
     CreateVideoEncodeAcceleratorCallback vea_create_callback;
   };
@@ -65,6 +65,11 @@ class WiFiDisplayVideoEncoder : public WiFiDisplayMediaEncoder {
   void RequestIDRPicture();
 
  protected:
+  // A factory method that creates a new encoder instance which uses Video
+  // Encode Accelerator (VEA) for encoding.
+  static void CreateVEA(const InitParameters& params,
+                        const VideoEncoderCallback& encoder_callback);
+
   explicit WiFiDisplayVideoEncoder(
       scoped_refptr<base::SingleThreadTaskRunner> media_task_runner);
   ~WiFiDisplayVideoEncoder() override;