Move optional.h to webrtc/api/
We use Optional in our public API, so its header should be in
webrtc/api/.
BUG=webrtc:8205
Review-Url: https://codereview.webrtc.org/3011943002
Cr-Commit-Position: refs/heads/master@{#19693}
diff --git a/webrtc/sdk/BUILD.gn b/webrtc/sdk/BUILD.gn
index ff97082..086ce49 100644
--- a/webrtc/sdk/BUILD.gn
+++ b/webrtc/sdk/BUILD.gn
@@ -183,6 +183,7 @@
":common_objc",
":videotracksource_objc",
"../api:libjingle_peerconnection_api",
+ "../api:optional",
"../common_video",
"../media:rtc_media_base",
"../rtc_base:rtc_base",