Reduce copying in sending service responses.

runtime/vm/timeline.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.
 
 #ifndef PRODUCT
 
 #include <cstdlib>
 
 #include "vm/atomic.h"
 #include "vm/isolate.h"
@@ skipping 1162 matching lines @@
     return;
   }
   free(filename);
 
   JSONStream js;
   TimelineEventFilter filter;
   PrintTraceEvent(&js, &filter);
   // Steal output from JSONStream.
   char* output = NULL;
   intptr_t output_length = 0;
-  js.Steal(const_cast<const char**>(&output), &output_length);
+  js.Steal(&output, &output_length);
   (*file_write)(output, output_length, file);
   // Free the stolen output.
   free(output);
   (*file_close)(file);
 
   return;
 }
 
 
 int64_t TimelineEventRecorder::GetNextAsyncId() {
@@ skipping 494 matching lines @@
 TimelineEventBlock* TimelineEventBlockIterator::Next() {
   ASSERT(current_ != NULL);
   TimelineEventBlock* r = current_;
   current_ = current_->next();
   return r;
 }
 
 }  // namespace dart
 
 #endif  // !PRODUCT