Add OnBeforeTraceLogDisabled notification to EnabledStateObserver

base/debug/trace_event_impl.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 "base/debug/trace_event_impl.h"
 
 #include <algorithm>
 
 #include "base/base_switches.h"
 #include "base/bind.h"
@@ skipping 1515 matching lines @@
 
   if (!IsEnabled())
     return;
 
   if (dispatching_to_observer_list_) {
     DLOG(ERROR)
         << "Cannot manipulate TraceLog::Enabled state from an observer.";
     return;
   }
 
+  dispatching_to_observer_list_ = true;
+  std::vector<EnabledStateObserver*> observer_list =
+      enabled_state_observer_list_;
+
+  {
+    // Dispatch to observers outside the lock in case the observer triggers a
+    // trace event.
+    AutoUnlock unlock(lock_);
+    for (size_t i = 0; i < observer_list.size(); ++i)
+      observer_list[i]->OnBeforeTraceLogDisabled();
+  }
+  dispatching_to_observer_list_ = false;
+
   mode_ = DISABLED;
 
   if (sampling_thread_.get()) {
     // Stop the sampling thread.
     sampling_thread_->Stop();
     lock_.Release();
     PlatformThread::Join(sampling_thread_handle_);
     lock_.Acquire();
     sampling_thread_handle_ = PlatformThreadHandle();
     sampling_thread_.reset();
   }
 
   category_filter_.Clear();
   subtle::NoBarrier_Store(&watch_category_, 0);
   watch_event_name_ = "";
   UpdateCategoryGroupEnabledFlags();
   AddMetadataEventsWhileLocked();
 
   dispatching_to_observer_list_ = true;
-  std::vector<EnabledStateObserver*> observer_list =
-      enabled_state_observer_list_;
-
   {
     // Dispatch to observers outside the lock in case the observer triggers a
     // trace event.
     AutoUnlock unlock(lock_);
     for (size_t i = 0; i < observer_list.size(); ++i)
       observer_list[i]->OnTraceLogDisabled();
   }
   dispatching_to_observer_list_ = false;
 }
 
@@ skipping 994 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