video: use VideoSettings for OSX

it is necessary to save preferences in dring.yml

Change-Id: I037d7e6bb122b3521a59c01c69e8895445f8abd2
Tuleap: #364
diff --git a/src/media/video/osxvideo/video_device_impl.mm b/src/media/video/osxvideo/video_device_impl.mm
index f298e15..5795fb9 100644
--- a/src/media/video/osxvideo/video_device_impl.mm
+++ b/src/media/video/osxvideo/video_device_impl.mm
@@ -142,6 +142,13 @@
 
     settings.name = [[avDevice_ localizedName] UTF8String];
 
+    auto format = [avDevice_ activeFormat];
+    auto frameRate = (AVFrameRateRange*)
+                    [format.videoSupportedFrameRateRanges objectAtIndex:0];
+    settings.framerate = frameRate.maxFrameRate;
+    settings.video_size = std::to_string(current_size_.width) +
+        "x" + std::to_string(current_size_.height);
+
     return settings;
 }