Remove the expat and jsoncpp to reduce the binary size.

webrtc/examples/BUILD.gn

Index: webrtc/examples/BUILD.gn
diff --git a/webrtc/examples/BUILD.gn b/webrtc/examples/BUILD.gn
index 10deaf27c42294e40868a989c5af43bd0638c5c7..bc1b20661520718ae88b575a069fd20039f7e847 100644
--- a/webrtc/examples/BUILD.gn
+++ b/webrtc/examples/BUILD.gn
@@ -527,15 +527,13 @@ if (is_linux || is_win) {
       "//webrtc/api:video_frame_api",
       "//webrtc/base:rtc_base",
       "//webrtc/base:rtc_base_approved",
+      "//webrtc/base:rtc_json",
       "//webrtc/media:rtc_media",
       "//webrtc/modules/video_capture:video_capture_module",
       "//webrtc/pc:libjingle_peerconnection",
       "//webrtc/system_wrappers:field_trial_default",
       "//webrtc/system_wrappers:metrics_default",
     ]
-    if (rtc_build_json) {
-      deps += [ "//third_party/jsoncpp" ]
-    }
   }
 
   rtc_executable("peerconnection_server") {