Add the streamListen and streamCancel rpcs to the vm service.

runtime/vm/service_event.h

Index: runtime/vm/service_event.h
diff --git a/runtime/vm/service_event.h b/runtime/vm/service_event.h
index e74ee66f2929dd039c794600aba734073968312f..aefbc25ab4efa83e9a9fbe3b4166600ffe085423 100644
--- a/runtime/vm/service_event.h
+++ b/runtime/vm/service_event.h
@@ -24,13 +24,12 @@ class ServiceEvent {
     kPauseInterrupted,
     kPauseException,
     kResume,
-
     kBreakpointAdded,
     kBreakpointResolved,
     kBreakpointRemoved,
+    kInspect,
 
     kGC,
-    kInspect,
 
     kIllegal,
   };
@@ -50,6 +49,8 @@ class ServiceEvent {
 
   EventType type() const { return type_; }
 
+  const char* stream_id() const;
+
   SourceBreakpoint* breakpoint() const {
     return breakpoint_;
   }