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

runtime/observatory/lib/src/service/object.dart

Index: runtime/observatory/lib/src/service/object.dart
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index 8c9717faa4b309ea17fb9a407a6719bcf3440355..b6c239d3d1ec30f08b08e126db258557d1221873 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -1171,6 +1171,8 @@ class Isolate extends ServiceObjectOwner with Coverage {
 
   @observable bool ioEnabled = false;
 
+  final List<String> extensionRPCs = new List<String>();
+
   Map<String,ServiceObject> _cache = new Map<String,ServiceObject>();
   final TagProfile tagProfile = new TagProfile(20);
 
@@ -1436,6 +1438,11 @@ class Isolate extends ServiceObjectOwner with Coverage {
     if (savedStartTime == null) {
       vm._buildIsolateList();
     }
+
+    extensionRPCs.clear();
+    if (map['extensionRPCs'] != null) {
+      extensionRPCs.addAll(map['extensionRPCs']);
+    }
   }
 
   Future<TagProfile> updateTagProfile() {
@@ -1884,6 +1891,7 @@ class ServiceEvent extends ServiceObject {
   static const kIsolateRunnable        = 'IsolateRunnable';
   static const kIsolateExit            = 'IsolateExit';
   static const kIsolateUpdate          = 'IsolateUpdate';
+  static const kServiceExtensionAdded  = 'ServiceExtensionAdded';
   static const kPauseStart             = 'PauseStart';
   static const kPauseExit              = 'PauseExit';
   static const kPauseBreakpoint        = 'PauseBreakpoint';
@@ -1910,6 +1918,7 @@ class ServiceEvent extends ServiceObject {
   @observable DateTime timestamp;
   @observable Breakpoint breakpoint;
   @observable Frame topFrame;
+  @observable String extensionRPC;
   @observable Instance exception;
   @observable Instance asyncContinuation;
   @observable bool atAsyncJump;
@@ -1952,6 +1961,9 @@ class ServiceEvent extends ServiceObject {
         breakpoint = pauseBpts[0];
       }
     }
+    if (map['extensionRPC'] != null) {
+      extensionRPC = map['extensionRPC'];
+    }
     topFrame = map['topFrame'];
     if (map['exception'] != null) {
       exception = map['exception'];