Use relative paths in GN files.

webrtc/modules/audio_processing/BUILD.gn

Index: webrtc/modules/audio_processing/BUILD.gn
diff --git a/webrtc/modules/audio_processing/BUILD.gn b/webrtc/modules/audio_processing/BUILD.gn
index 3af019e49e895453a62b27ddabfad869445d5110..92a8f177a02040fa175db389096617f8436a9576 100644
--- a/webrtc/modules/audio_processing/BUILD.gn
+++ b/webrtc/modules/audio_processing/BUILD.gn
@@ -507,7 +507,7 @@ if (rtc_include_tests) {
     # gets additional generated targets which would require many lines here to
     # cover (which would be confusing to read and hard to maintain).
     if (!is_android && !is_ios) {
-      visibility = [ "//webrtc/modules:modules_unittests" ]
+      visibility = [ "..:modules_unittests" ]
     }
     sources = [
       "aec/echo_cancellation_unittest.cc",
@@ -686,7 +686,7 @@ if (rtc_include_tests) {
     # gets additional generated targets which would require many lines here to
     # cover (which would be confusing to read and hard to maintain).
     if (!is_android && !is_ios) {
-      visibility = [ "//webrtc:webrtc_perf_tests" ]
+      visibility = [ "../..:webrtc_perf_tests" ]
     }
     sources = [
       "audio_processing_performance_unittest.cc",