tracing_controller: Eliminates extra parameter of StartAgentTracingDone

content/browser/tracing/tracing_controller_impl.cc

 // Copyright (c) 2013 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/tracing/tracing_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/cpu.h"
 #include "base/files/file_util.h"
 #include "base/json/string_escape.h"
 #include "base/macros.h"
@@ skipping 234 matching lines @@
 #endif
   }
 
   // TraceLog may have been enabled in startup tracing before threads are ready.
   if (TraceLog::GetInstance()->IsEnabled())
     return true;
   return StartAgentTracing(trace_config);
 }
 
 void TracingControllerImpl::OnStartAgentTracingDone(
-    const TraceConfig& trace_config,
-    const StartTracingDoneCallback& callback) {
+    const TraceConfig& trace_config) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   TRACE_EVENT_API_ADD_METADATA_EVENT("IsTimeTicksHighResolution", "value",
                                      base::TimeTicks::IsHighResolution());
   TRACE_EVENT_API_ADD_METADATA_EVENT("TraceConfig", "value",
                                      trace_config.AsConvertableToTraceFormat());
 
   // Notify all child processes.
   for (TraceMessageFilterSet::iterator it = trace_message_filters_.begin();
       it != trace_message_filters_.end(); ++it) {
     it->get()->SendBeginTracing(trace_config);
   }
 
-  if (!callback.is_null())
-    callback.Run();
-
-  start_tracing_done_callback_.Reset();
+  if (!start_tracing_done_callback_.is_null()) {
+    start_tracing_done_callback_.Run();
+    start_tracing_done_callback_.Reset();
+  }
 }
 
 bool TracingControllerImpl::StopTracing(
     const scoped_refptr<TraceDataSink>& trace_data_sink) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   if (trace_data_sink) {
     if (TraceLog::GetInstance()->GetCurrentTraceConfig()
         .IsArgumentFilterEnabled()) {
       scoped_ptr<TracingDelegate> delegate(
@@ skipping 592 matching lines @@
 std::string TracingControllerImpl::GetTraceEventLabel() {
   return kChromeTraceLabel;
 }
 
 bool TracingControllerImpl::StartAgentTracing(
     const base::trace_event::TraceConfig& trace_config) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   base::Closure on_start_tracing_done_callback =
       base::Bind(&TracingControllerImpl::OnStartAgentTracingDone,
-                 base::Unretained(this),
-                 trace_config, start_tracing_done_callback_);
+                 base::Unretained(this), trace_config);
   if (!BrowserThread::PostTask(
           BrowserThread::FILE, FROM_HERE,
           base::Bind(&TracingControllerImpl::SetEnabledOnFileThread,
                      base::Unretained(this), trace_config,
                      base::trace_event::TraceLog::RECORDING_MODE,
                      on_start_tracing_done_callback))) {
     // BrowserThread::PostTask fails if the threads haven't been created yet,
     // so it should be safe to just use TraceLog::SetEnabled directly.
     base::trace_event::TraceLog::GetInstance()->SetEnabled(
         trace_config, base::trace_event::TraceLog::RECORDING_MODE);
@@ skipping 227 matching lines @@
   is_monitoring_ = is_monitoring;
 #if !defined(OS_ANDROID)
   for (std::set<TracingUI*>::iterator it = tracing_uis_.begin();
        it != tracing_uis_.end(); it++) {
     (*it)->OnMonitoringStateChanged(is_monitoring);
   }
 #endif
 }
 
 }  // namespace content