Add trace_service_pause_events flag and paused at exit tracing

R=keertip@google.com, turnidge@google.com

Review URL: https://codereview.chromium.org//271893002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@35944 260f80e4-7a28-3924-810f-c04153c831b5

runtime/bin/vmservice/server.dart

@@ -127,7 +127,7 @@ class Server {
       _server = s;
       _server.listen(_requestHandler);
       if (display_message) {
-        print('VMService listening on $ip:$port');
+        print('Observatory listening on http://$ip:$port');
       }
       return s;
     });

runtime/vm/message_handler.cc

@@ -9,7 +9,7 @@
 namespace dart {
 
 DECLARE_FLAG(bool, trace_isolates);
-
+DECLARE_FLAG(bool, trace_service_pause_events);
 
 class MessageHandlerTask : public ThreadPool::Task {
  public:
@@ -231,6 +231,10 @@ void MessageHandler::TaskCallback() {
 
     if (!ok || !HasLivePorts()) {
       if (pause_on_exit()) {
+        if (FLAG_trace_service_pause_events && !paused_on_exit_) {
+          OS::PrintErr("Isolate %s paused before exiting. "
+                       "Use the Observatory to release it.\n", name());
+        }
         paused_on_exit_ = true;
       } else {
         if (FLAG_trace_isolates) {

runtime/vm/service.cc

@@ -32,6 +32,8 @@
 namespace dart {
 
 DEFINE_FLAG(bool, trace_service, false, "Trace VM service requests.");
+DEFINE_FLAG(bool, trace_service_pause_events, false,
+            "Trace VM service isolate pause events.");
 DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(bool, enable_asserts);
 

tests/standalone/vmservice/test_helper.dart

@@ -140,7 +140,7 @@ class TestLauncher {
       var first = true;
       process.stdout.transform(UTF8.decoder)
                     .transform(new LineSplitter()).listen((line) {
-        if (line.startsWith('VMService listening on ')) {
+        if (line.startsWith('Observatory listening on http://')) {
           RegExp portExp = new RegExp(r"\d+.\d+.\d+.\d+:(\d+)");
           var port = portExp.firstMatch(line).group(1);
           portNumber = int.parse(port);