Fix Observatory timeline export to be compatible with about:tracing

runtime/vm/profiler_service.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/profiler_service.h"
 
 #include "vm/growable_array.h"
 #include "vm/hash_map.h"
 #include "vm/log.h"
 #include "vm/native_symbol.h"
@@ skipping 2401 matching lines @@
   }
   {
     JSONArray events(&obj, "traceEvents");
     intptr_t pid = OS::ProcessId();
     intptr_t isolate_id = reinterpret_cast<intptr_t>(isolate_);
     for (intptr_t sample_index = 0; sample_index < samples_->length();
          sample_index++) {
       ProcessedSample* sample = samples_->At(sample_index);
       JSONObject event(&events);
       event.AddProperty("ph", "P");  // kind = sample event
+      // Add a blank name to keep about:tracing happy.
+      event.AddProperty("name", "");
       event.AddProperty64("pid", pid);
       event.AddProperty64("tid", OSThread::ThreadIdToIntPtr(sample->tid()));
       event.AddPropertyTimeMicros("ts", sample->timestamp());
       event.AddProperty("cat", "Dart");
 
       ProfileTrieNode* trie = sample->timeline_trie();
       ASSERT(trie->frame_id() != -1);
       event.AddPropertyF("sf", "%" Pd "-%" Pd, isolate_id, trie->frame_id());
     }
   }
@@ skipping 332 matching lines @@
   // Disable thread interrupts while processing the buffer.
   DisableThreadInterruptsScope dtis(thread);
 
   ClearProfileVisitor clear_profile(isolate);
   sample_buffer->VisitSamples(&clear_profile);
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart