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

runtime/vm/service_event.h

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SERVICE_EVENT_H_
 #define VM_SERVICE_EVENT_H_
 
 #include "vm/debugger.h"
 
 class DebuggerEvent;
 
 namespace dart {
 
 class ServiceEvent {
  public:
   enum EventType {
     kIsolateStart,       // New isolate has started
     kIsolateExit,        // Isolate has exited
     kIsolateUpdate,      // Isolate identity information has changed
 
     kPauseStart,         // --pause-isolates-on-start
     kPauseExit,          // --pause-isolates-on-exit
     kPauseBreakpoint,
     kPauseInterrupted,
     kPauseException,
     kResume,
-
     kBreakpointAdded,
     kBreakpointResolved,
     kBreakpointRemoved,
+    kInspect,
 
     kGC,
-    kInspect,
 
     kIllegal,
   };
 
   ServiceEvent(Isolate* isolate, EventType event_type)
       : isolate_(isolate),
         type_(event_type),
         breakpoint_(NULL),
         top_frame_(NULL),
         exception_(NULL),
         inspectee_(NULL),
         gc_stats_(NULL) {}
 
   explicit ServiceEvent(const DebuggerEvent* debugger_event);
 
   Isolate* isolate() const { return isolate_; }
 
   EventType type() const { return type_; }
 
+  const char* stream_id() const;
+
   Breakpoint* breakpoint() const {
     return breakpoint_;
   }
   void set_breakpoint(Breakpoint* bpt) {
     ASSERT(type() == kPauseBreakpoint ||
            type() == kBreakpointAdded ||
            type() == kBreakpointResolved ||
            type() == kBreakpointRemoved);
     breakpoint_ = bpt;
   }
@@ skipping 43 matching lines @@
   Breakpoint* breakpoint_;
   ActivationFrame* top_frame_;
   const Object* exception_;
   const Object* inspectee_;
   const Heap::GCStats* gc_stats_;
 };
 
 }  // namespace dart
 
 #endif  // VM_SERVICE_EVENT_H_