GN: Tighten up test target visibility + refactorings

webrtc/api/BUILD.gn

Index: webrtc/api/BUILD.gn
diff --git a/webrtc/api/BUILD.gn b/webrtc/api/BUILD.gn
index fdd441a5d5e646471428acd261251f11c8702164..b8ad90505ffa57c6dc688c038e3f66b7b054b48f 100644
--- a/webrtc/api/BUILD.gn
+++ b/webrtc/api/BUILD.gn
@@ -243,6 +243,13 @@ if (rtc_include_tests) {
 
   rtc_source_set("rtc_api_unittests") {
     testonly = true
+
+    # Skip restricting visibility on mobile platforms since the tests on those
+    # 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:rtc_unittests" ]
+    }
     sources = [
       "ortc/mediadescription_unittest.cc",
       "ortc/sessiondescription_unittest.cc",