2nd attempt at adding streamListen/streamCancel to the service protocol.

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
diff --git a/runtime/vm/debugger.cc b/runtime/vm/debugger.cc
index d5d82c729f445a695b2614ff4e91e58244f31bb7..939dafdd8fdfab7866e6af741d3633fe4051c6e6 100644
--- a/runtime/vm/debugger.cc
+++ b/runtime/vm/debugger.cc
@@ -235,7 +235,32 @@ ActivationFrame::ActivationFrame(
 
 
 bool Debugger::HasEventHandler() {
-  return (event_handler_ != NULL) || Service::NeedsEvents();
+  return ((event_handler_ != NULL) ||
+          Service::NeedsIsolateEvents() ||
+          Service::NeedsDebugEvents());
+}
+
+
+static bool ServiceNeedsDebuggerEvent(DebuggerEvent::EventType type) {
+  switch (type) {
+    case DebuggerEvent::kBreakpointResolved:
+      // kBreakpointResolved events are handled differently in the vm
+      // service, so suppress them here.
+      return false;
+
+    case DebuggerEvent::kBreakpointReached:
+    case DebuggerEvent::kExceptionThrown:
+    case DebuggerEvent::kIsolateInterrupted:
+      return Service::NeedsDebugEvents();
+
+    case DebuggerEvent::kIsolateCreated:
+    case DebuggerEvent::kIsolateShutdown:
+      return Service::NeedsIsolateEvents();
+
+    default:
+      UNREACHABLE();
+      return false;
+  }
 }
 
 
@@ -247,8 +272,7 @@ void Debugger::InvokeEventHandler(DebuggerEvent* event) {
   //
   // kBreakpointResolved events are handled differently in the vm
   // service, so suppress them here.
-  if (Service::NeedsEvents() &&
-      (event->type() != DebuggerEvent::kBreakpointResolved)) {
+  if (ServiceNeedsDebuggerEvent(event->type())) {
     ServiceEvent service_event(event);
     Service::HandleEvent(&service_event);
   }
@@ -260,7 +284,7 @@ void Debugger::InvokeEventHandler(DebuggerEvent* event) {
     (*event_handler_)(event);
   }
 
-  if (Service::NeedsEvents() && event->IsPauseEvent()) {
+  if (ServiceNeedsDebuggerEvent(event->type()) && event->IsPauseEvent()) {
     // If we were paused, notify the service that we have resumed.
     ServiceEvent service_event(event->isolate(), ServiceEvent::kResume);
     service_event.set_top_frame(event->top_frame());
@@ -303,7 +327,7 @@ void Debugger::SignalIsolateInterrupted() {
 // than the regular debugger breakpoint notifications.
 static void SendServiceBreakpointEvent(ServiceEvent::EventType type,
                                        Breakpoint* bpt) {
-  if (Service::NeedsEvents()) {
+  if (Service::NeedsDebugEvents()) {
     ServiceEvent service_event(Isolate::Current(), type);
     service_event.set_breakpoint(bpt);
     Service::HandleEvent(&service_event);