Get net_watcher running again

It needs a base::TaskScheduler.

Change-Id: I20f1f92a62c6c5e63990d6d1bb67b7ca063317ca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539921
Commit-Queue: Paul Jensen <pauljensen@chromium.org>
Auto-Submit: Paul Jensen <pauljensen@chromium.org>
Reviewed-by: Josh Karlin <jkarlin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644420}

net/tools/net_watcher/net_watcher.cc

@@ -23,6 +23,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/string_split.h"
+#include "base/task/task_scheduler/task_scheduler.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "net/base/network_change_notifier.h"
@@ -155,6 +156,8 @@ int main(int argc, char* argv[]) {
   // Just make the main message loop the network loop.
   base::MessageLoopForIO network_loop;
 
+  base::TaskScheduler::CreateAndStartWithDefaultParams("NetWatcher");
+
   NetWatcher net_watcher;
 
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)