Cleanup: Remove unneeded browser_thread.h includes in contents.

content/browser/devtools/devtools_tracing_handler.cc

 // 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.
 
 #include "content/browser/devtools/devtools_tracing_handler.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/location.h"
 #include "base/values.h"
 #include "content/browser/devtools/devtools_http_handler_impl.h"
-#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/trace_controller.h"
 #include "content/public/browser/trace_subscriber.h"
 
 namespace content {
 
 DevToolsTracingHandler::DevToolsTracingHandler()
     : has_completed_(false),
       buffer_data_size_(0) {
 }
 
@@ skipping 71 matching lines @@
     ret.append(*i);
   }
   buffer_.clear();
   has_completed_ = false;
   buffer_data_size_ = 0;
 
   return base::Value::CreateStringValue(ret);
 }
 
 }  // namespace content