Add OnBeforeTraceLogDisabled notification to EnabledStateObserver

base/debug/trace_event_impl.cc

Index: base/debug/trace_event_impl.cc
diff --git a/base/debug/trace_event_impl.cc b/base/debug/trace_event_impl.cc
index 5c521d462fe0e73c766d801f1b4340ad2d82670f..5341ba3a1867861cb444cd0009fa6dfea0d49f64 100644
--- a/base/debug/trace_event_impl.cc
+++ b/base/debug/trace_event_impl.cc
@@ -1533,6 +1533,19 @@ void TraceLog::SetDisabledWhileLocked() {
     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()) {
@@ -1552,9 +1565,6 @@ void TraceLog::SetDisabledWhileLocked() {
   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.