Use relative paths in GN files.

webrtc/call/BUILD.gn

Index: webrtc/call/BUILD.gn
diff --git a/webrtc/call/BUILD.gn b/webrtc/call/BUILD.gn
index 6a50ea09a2a0043a12e66acb1d551fb2830c4b3a..c26c761a10a820ddeb051e2e09571d6c0bfdd59b 100644
--- a/webrtc/call/BUILD.gn
+++ b/webrtc/call/BUILD.gn
@@ -130,7 +130,7 @@ 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:video_engine_tests" ]
+      visibility = [ "..:video_engine_tests" ]
     }
     sources = [
       "bitrate_allocator_unittest.cc",
@@ -180,7 +180,7 @@ 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 = [
       "call_perf_tests.cc",
@@ -200,13 +200,13 @@ if (rtc_include_tests) {
       "../system_wrappers:metrics_default",
       "../test:direct_transport",
       "../test:fake_audio_device",
+      "../test:field_trial",
+      "../test:test_common",
       "../test:test_support",
       "../test:video_test_common",
       "../video",
       "../voice_engine",
       "//testing/gtest",
-      "//webrtc/test:field_trial",
-      "//webrtc/test:test_common",
     ]
     if (!build_with_chromium && is_clang) {
       # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).