Move sequence_number_utils.h to rtc_base/

Bug: webrtc:8440
Change-Id: I36e70da6ce70b95db7d3fce8b0013bff5c795bfc
Reviewed-on: https://webrtc-review.googlesource.com/14860
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20429}
diff --git a/modules/video_coding/BUILD.gn b/modules/video_coding/BUILD.gn
index da3a593..48636e9 100644
--- a/modules/video_coding/BUILD.gn
+++ b/modules/video_coding/BUILD.gn
@@ -137,7 +137,6 @@
   sources = [
     "codecs/interface/video_codec_interface.h",
     "codecs/interface/video_error_codes.h",
-    "sequence_number_util.h",
     "utility/default_video_bitrate_allocator.cc",
     "utility/default_video_bitrate_allocator.h",
     "utility/frame_dropper.cc",
@@ -524,7 +523,6 @@
       "protection_bitrate_calculator_unittest.cc",
       "receiver_unittest.cc",
       "rtp_frame_reference_finder_unittest.cc",
-      "sequence_number_util_unittest.cc",
       "session_info_unittest.cc",
       "test/stream_generator.cc",
       "test/stream_generator.h",
@@ -564,6 +562,7 @@
       "../../common_video:common_video",
       "../../rtc_base:rtc_base",
       "../../rtc_base:rtc_base_approved",
+      "../../rtc_base:rtc_numerics",
       "../../rtc_base:rtc_task_queue",
       "../../system_wrappers:metrics_default",
       "../../system_wrappers:system_wrappers",