Use explicit conversion to base::Optional in MSVS::GetCurrentFormatImpl implementations.

content/renderer/pepper/pepper_media_stream_video_track_host.cc

Index: content/renderer/pepper/pepper_media_stream_video_track_host.cc
diff --git a/content/renderer/pepper/pepper_media_stream_video_track_host.cc b/content/renderer/pepper/pepper_media_stream_video_track_host.cc
index 42ae7eb40b54274e0ab58a0fee56caff79bd3aa8..548b13809a00ca8e9fd042a41f11f794b5948681 100644
--- a/content/renderer/pepper/pepper_media_stream_video_track_host.cc
+++ b/content/renderer/pepper/pepper_media_stream_video_track_host.cc
@@ -447,9 +447,10 @@ class PepperMediaStreamVideoTrackHost::VideoSource final
       const override {
     DCHECK(!IsOldVideoConstraints());
     if (host_) {
-      return media::VideoCaptureFormat(
-          host_->plugin_frame_size_, kDefaultOutputFrameRate,
-          ToPixelFormat(host_->plugin_frame_format_));
+      return base::Optional<media::VideoCaptureFormat>(
+          media::VideoCaptureFormat(
+              host_->plugin_frame_size_, kDefaultOutputFrameRate,
+              ToPixelFormat(host_->plugin_frame_format_)));
     }
     return base::Optional<media::VideoCaptureFormat>();
   }