Expose Service Describer in Dart mojo package

mojo/dart/packages/mojo_services/lib/tracing/tracing.mojom.dart

Index: mojo/dart/packages/mojo_services/lib/tracing/tracing.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/tracing/tracing.mojom.dart b/mojo/dart/packages/mojo_services/lib/tracing/tracing.mojom.dart
index 5fe70c585c645e41b459463ba5ca3148d98585c8..83009a4e22792fcfb16d1986d08a1b6c242ca26c 100644
--- a/mojo/dart/packages/mojo_services/lib/tracing/tracing.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/tracing/tracing.mojom.dart
@@ -385,11 +385,14 @@ const int _TraceProvider_stopTracingName = 1;
 
 
 class _TraceProviderServiceDescription implements service_describer.ServiceDescription {
-  dynamic getTopLevelInterface([Function responseFactory]) => null;
+  dynamic getTopLevelInterface([Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) => null;
+  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getAllTypeDefinitions([Function responseFactory]) => null;
+  dynamic getAllTypeDefinitions([Function responseFactory]) =>
+      responseFactory(null);
 }
 
 abstract class TraceProvider {
@@ -575,8 +578,13 @@ class TraceProviderStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _TraceProviderServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _TraceProviderServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _TraceRecorder_recordName = 0;
@@ -584,11 +592,14 @@ const int _TraceRecorder_recordName = 0;
 
 
 class _TraceRecorderServiceDescription implements service_describer.ServiceDescription {
-  dynamic getTopLevelInterface([Function responseFactory]) => null;
+  dynamic getTopLevelInterface([Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) => null;
+  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getAllTypeDefinitions([Function responseFactory]) => null;
+  dynamic getAllTypeDefinitions([Function responseFactory]) =>
+      responseFactory(null);
 }
 
 abstract class TraceRecorder {
@@ -759,8 +770,13 @@ class TraceRecorderStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _TraceRecorderServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _TraceRecorderServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _TraceCollector_startName = 0;
@@ -769,11 +785,14 @@ const int _TraceCollector_stopAndFlushName = 1;
 
 
 class _TraceCollectorServiceDescription implements service_describer.ServiceDescription {
-  dynamic getTopLevelInterface([Function responseFactory]) => null;
+  dynamic getTopLevelInterface([Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) => null;
+  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getAllTypeDefinitions([Function responseFactory]) => null;
+  dynamic getAllTypeDefinitions([Function responseFactory]) =>
+      responseFactory(null);
 }
 
 abstract class TraceCollector {
@@ -959,8 +978,13 @@ class TraceCollectorStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _TraceCollectorServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _TraceCollectorServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }