Create //webrtc/api:libjingle_peerconnection_api + refactorings.

webrtc/BUILD.gn

Index: webrtc/BUILD.gn
diff --git a/webrtc/BUILD.gn b/webrtc/BUILD.gn
index f8a271d407d58fcf6d2c9588d8670d5cfd28b427..6f061a97ff1751e23bbcbb976c416adbe304b0b4 100644
--- a/webrtc/BUILD.gn
+++ b/webrtc/BUILD.gn
@@ -295,7 +295,6 @@ if (!build_with_chromium) {
         ":video_engine_tests",
         ":webrtc_nonparallel_tests",
         ":webrtc_perf_tests",
-        "api:peerconnection_unittests",
         "common_audio:common_audio_unittests",
         "common_video:common_video_unittests",
         "libjingle:xmllite_xmpp_unittests",
@@ -306,6 +305,7 @@ if (!build_with_chromium) {
         "modules/audio_processing:audio_processing_tests",
         "modules/rtp_rtcp:test_packet_masks_metrics",
         "modules/video_capture:video_capture_internal_impl",
+        "pc:peerconnection_unittests",
         "pc:rtc_pc_unittests",
         "stats:rtc_stats_unittests",
         "system_wrappers:system_wrappers_unittests",
@@ -319,7 +319,7 @@ if (!build_with_chromium) {
       if (is_android) {
         deps += [
           ":android_junit_tests",
-          "api:libjingle_peerconnection_android_unittest",
+          "pc:libjingle_peerconnection_android_unittest",
         ]
       } else {
         deps += [ "modules/video_capture:video_capture_tests" ]