Provide list of service protocol extensions in isolate and emit an event when one is registered

runtime/vm/service_event.cc

Index: runtime/vm/service_event.cc
diff --git a/runtime/vm/service_event.cc b/runtime/vm/service_event.cc
index bad3583c674a793ef2d7cb66b669b512287826d8..8a76e646c1aea3697cd3143a619f1a060a7a0007 100644
--- a/runtime/vm/service_event.cc
+++ b/runtime/vm/service_event.cc
@@ -40,6 +40,7 @@ ServiceEvent::ServiceEvent(Isolate* isolate, EventKind event_kind)
       embedder_stream_id_(NULL),
       breakpoint_(NULL),
       top_frame_(NULL),
+      extension_name_(NULL),
       exception_(NULL),
       async_continuation_(NULL),
       at_async_jump_(false),
@@ -62,6 +63,7 @@ ServiceEvent::ServiceEvent(const DebuggerEvent* debugger_event)
       kind_(TranslateEventKind(debugger_event->type())),
       breakpoint_(NULL),
       top_frame_(NULL),
+      extension_name_(NULL),
       exception_(NULL),
       async_continuation_(NULL),
       inspectee_(NULL),
@@ -101,6 +103,8 @@ const char* ServiceEvent::KindAsCString() const {
       return "IsolateExit";
     case kIsolateUpdate:
       return "IsolateUpdate";
+    case kIsolateServiceExtensionRegistered:
+      return "IsolateServiceExtensionRegistered";

[turnidge, 2015/12/16 18:47:25]

This name is a little long.  How about dropping "Isolate" and calling it
"ServiceExtensionRegistered".  It can still go on the Isolate stream without the
word Isolate in its name.

The name "ServiceExtensionAdded" would be shorter yet (and consistent with
BreakpointAdded) and it would leave the door open for adding a
"ServiceExtensionRemoved" event in the future if we want without using the bulky
verb "unregistered".  Your call.

[Cutch, 2015/12/16 21:19:56]

Done.

     case kPauseStart:
       return "PauseStart";
     case kPauseExit:
@@ -147,6 +151,7 @@ const char* ServiceEvent::stream_id() const {
     case kIsolateRunnable:
     case kIsolateExit:
     case kIsolateUpdate:
+    case kIsolateServiceExtensionRegistered:
       return Service::isolate_stream.id();
 
     case kPauseStart:
@@ -181,6 +186,10 @@ const char* ServiceEvent::stream_id() const {
 void ServiceEvent::PrintJSON(JSONStream* js) const {
   JSONObject jsobj(js);
   PrintJSONHeader(&jsobj);
+  if (kind() == kIsolateServiceExtensionRegistered) {
+    ASSERT(extension_name_ != NULL);
+    jsobj.AddProperty("serviceExtensionName", extension_name_->ToCString());
+  }
   if (kind() == kPauseBreakpoint) {
     JSONArray jsarr(&jsobj, "pauseBreakpoints");
     // TODO(rmacnak): If we are paused at more than one breakpoint,