test: fix typo

BUG=none

Change-Id: Ie50a5666c2db08579580c3b75475171ab884ede5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176124
Reviewed-by: Oskar Sundbom <ossu@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31357}
diff --git a/pc/media_session_unittest.cc b/pc/media_session_unittest.cc
index ba4db0a..8b5e320 100644
--- a/pc/media_session_unittest.cc
+++ b/pc/media_session_unittest.cc
@@ -4599,7 +4599,7 @@
   // properly.
   send_codecs[1].channels = 0;
 
-  // Alther iLBC receive codec to be lowercase, to test that case conversions
+  // Alter iLBC receive codec to be lowercase, to test that case conversions
   // are handled properly.
   recv_codecs[2].name = "ilbc";