components: Fix components_tracing.gyp to follow the same pattern of the other gyp files.

components/tracing_untrusted.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'includes': [
     '../build/common_untrusted.gypi',
   ],
   'conditions': [
@@ skipping 21 matching lines @@
             'tracing/child_trace_message_filter.cc',
             'tracing/child_trace_message_filter.h',
             'tracing/tracing_messages.cc',
             'tracing/tracing_messages.h',
           ],
         },
       ],
     }],
   ],
 }