Include 'fixedId' key when printing service ids

runtime/vm/json_stream.h

Index: runtime/vm/json_stream.h
diff --git a/runtime/vm/json_stream.h b/runtime/vm/json_stream.h
index 3c3bc9c1d3b83244f19c7a3f17a577179f7cb4b3..2aa195e85fb9e69e358c6c2a1b8acbc50e85aaca 100644
--- a/runtime/vm/json_stream.h
+++ b/runtime/vm/json_stream.h
@@ -122,7 +122,7 @@ class JSONStream : ValueObject {
   void PrintValue(Isolate* isolate, bool ref = true);
   bool PrintValueStr(const String& s, intptr_t limit);
 
-  void PrintServiceId(const char* name, const Object& o);
+  void PrintServiceId(const Object& o);
   void PrintPropertyBool(const char* name, bool b);
   void PrintProperty(const char* name, intptr_t i);
   void PrintProperty64(const char* name, int64_t i);
@@ -181,10 +181,12 @@ class JSONObject : public ValueObject {
     stream_->CloseObject();
   }
 
-  void AddServiceId(const char* name, const Object& o) const {
-    stream_->PrintServiceId(name, o);
+  void AddServiceId(const Object& o) const {
+    stream_->PrintServiceId(o);
   }
 
+  void AddFixedServiceId(const char* format, ...) const PRINTF_ATTRIBUTE(2, 3);
+
   void AddProperty(const char* name, bool b) const {
     stream_->PrintPropertyBool(name, b);
   }