Add tracing AutoOpenCloseEvent.

base/trace_event/trace_log.cc

 // Copyright 2015 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 "base/trace_event/trace_log.h"
 
 #include <algorithm>
 #include <cmath>
 #include <memory>
 #include <utility>
@@ skipping 814 matching lines @@
 
   if (!IsEnabled())
     return;
 
   if (dispatching_to_observer_list_) {
     DLOG(ERROR)
         << "Cannot manipulate TraceLog::Enabled state from an observer.";
     return;
   }
 
-  mode_ = DISABLED;
-
   if (sampling_thread_) {
     // Stop the sampling thread.
     sampling_thread_->Stop();
     lock_.Release();
     PlatformThread::Join(sampling_thread_handle_);
     lock_.Acquire();
     sampling_thread_handle_ = PlatformThreadHandle();
     sampling_thread_.reset();
   }
 
@@ skipping 11 matching lines @@
       enabled_state_observer_list_;
   std::map<AsyncEnabledStateObserver*, RegisteredAsyncObserver> observer_map =
       async_observers_;
 
   {
     // Dispatch to observers outside the lock in case the observer triggers a
     // trace event.
     AutoUnlock unlock(lock_);
     for (EnabledStateObserver* observer : observer_list)
       observer->OnTraceLogDisabled();
+    mode_ = DISABLED;
     for (const auto& it : observer_map) {
       it.second.task_runner->PostTask(
           FROM_HERE, Bind(&AsyncEnabledStateObserver::OnTraceLogDisabled,
                           it.second.observer));
     }
   }
   dispatching_to_observer_list_ = false;
 }
 
 int TraceLog::GetNumTracesRecorded() {
@@ skipping 1043 matching lines @@
 }
 
 ScopedTraceBinaryEfficient::~ScopedTraceBinaryEfficient() {
   if (*category_group_enabled_) {
     TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(category_group_enabled_, name_,
                                                 event_handle_);
   }
 }
 
 }  // namespace trace_event_internal