Split SocketWatcher and SocketWatcherFactory out of NQE

This is a simple refactoring CL, and does not involve any
functionality change.

BUG=616302

Review-Url: https://codereview.chromium.org/2024813003
Cr-Commit-Position: refs/heads/master@{#398250}
diff --git a/net/net.gypi b/net/net.gypi
index 0fd88482..d938c56 100644
--- a/net/net.gypi
+++ b/net/net.gypi
@@ -737,6 +737,10 @@
       'nqe/network_quality_observation.h',
       'nqe/network_quality_observation_source.h',
       'nqe/observation_buffer.h',
+      'nqe/socket_watcher.cc',
+      'nqe/socket_watcher.h',
+      'nqe/socket_watcher_factory.cc',
+      'nqe/socket_watcher_factory.h',
       'nqe/throughput_analyzer.cc',
       'nqe/throughput_analyzer.h',
       'nqe/weighted_observation.h',