Add first part of the network_tester functionality.

webrtc/tools/BUILD.gn

Index: webrtc/tools/BUILD.gn
diff --git a/webrtc/tools/BUILD.gn b/webrtc/tools/BUILD.gn
index 5a4c1af4be223929e017c2d70d974ee15169b92b..05b7adbf796bb6ac110b2bf455ced6aa4a8df4a2 100644
--- a/webrtc/tools/BUILD.gn
+++ b/webrtc/tools/BUILD.gn
@@ -36,6 +36,7 @@ group("tools") {
       public_deps += [
         ":event_log_visualizer",
         ":rtp_analyzer",
+        "network_tester",
       ]
     }
   }
@@ -311,6 +312,10 @@ if (rtc_include_tests) {
       "//testing/gtest",
     ]
 
+    if (rtc_enable_protobuf) {
+      deps += [ "network_tester:network_tester_unittests" ]
+    }
+
     data = tools_unittests_resources
     if (is_android) {
       deps += [ "//testing/android/native_test:native_test_support" ]