Implement 'print', 'up', 'down', and 'frame' commands in the Observatory debugger.

runtime/vm/service_isolate.cc

 // 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.
 
 #include "vm/service_isolate.h"
 
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/isolate.h"
@@ skipping 201 matching lines @@
 
     // Set the type of the OOB message.
     message.SetAt(0, Smi::Handle(isolate, Smi::New(Message::kServiceOOBMsg)));
 
     // Serialize message.
     uint8_t* data = NULL;
     MessageWriter writer(&data, &allocator, false);
     writer.WriteMessage(message);
 
     // TODO(turnidge): Throw an exception when the return value is false?
-    PortMap::PostMessage(new Message(sp.Id(), data, writer.BytesWritten(),
-                                     Message::kOOBPriority));
+    bool result = PortMap::PostMessage(
+        new Message(sp.Id(), data, writer.BytesWritten(),
+                    Message::kOOBPriority));
+    arguments->SetReturn(Bool::Get(result));
   }
 
   static void SendRootServiceMessage(Dart_NativeArguments args) {
     NativeArguments* arguments = reinterpret_cast<NativeArguments*>(args);
     Isolate* isolate = arguments->isolate();
     StackZone zone(isolate);
     HANDLESCOPE(isolate);
     GET_NON_NULL_NATIVE_ARGUMENT(Array, message, arguments->NativeArgAt(0));
     Service::HandleRootMessage(message);
   }
@@ skipping 443 matching lines @@
     return result;
   }
   Dart_Handle source = GetSource(url_string);
   if (Dart_IsError(source)) {
     return source;
   }
   return Dart_LoadSource(library, url, source, 0, 0);
 }
 
 }  // namespace dart