New file api/video/BUILD.gn

Build targets involving files under api/video/ are moved into this
file, from api/BUILD.gn. In addition, drop "_api" part of target
names, and move the header file api/videosinkinterface.h to
api/video/video_sink_interface.h.

Bug: webrtc:9253
Change-Id: I2896d3f063db8dff902bc29738578395b2fcc155
Reviewed-on: https://webrtc-review.googlesource.com/75500
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23207}
diff --git a/BUILD.gn b/BUILD.gn
index c1ccb5c..4f019c1 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -345,7 +345,7 @@
 
     if (build_with_mozilla) {
       deps += [
-        "api:video_frame_api",
+        "api/video:video_frame",
         "system_wrappers:field_trial_default",
         "system_wrappers:metrics_default",
       ]
@@ -381,7 +381,7 @@
     ":typedefs",
     "api:array_view",
     "api:optional",
-    "api:video_bitrate_allocation",
+    "api/video:video_bitrate_allocation",
     "rtc_base:checks",
     "rtc_base:deprecation",
     "rtc_base:stringutils",