GTTF: Add missing virtual destructors.

base/debug/trace_event_impl.h

 // 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.
 
 
 #ifndef BASE_DEBUG_TRACE_EVENT_IMPL_H_
 #define BASE_DEBUG_TRACE_EVENT_IMPL_H_
 
 #include "build/build_config.h"
 
@@ skipping 209 matching lines @@
     // Called just before the tracing system becomes
     // enabled. TraceLog::IsEnabled will return false at this point and trace
     // macros and methods called within the observer will deadlock.
     virtual void OnTraceLogWillEnable() { }
 
     // Called just before the tracing system disables. TraceLog::IsEnabled is
     // still false at this point TRACE macros will still be capturing
     // data. However, trace macros and methods called within the observer will
     // deadlock.
     virtual void OnTraceLogWillDisable() { }
+
+   protected:
+    virtual ~EnabledStateChangedObserver() { }
   };
   void AddEnabledStateObserver(EnabledStateChangedObserver* listener);
   void RemoveEnabledStateObserver(EnabledStateChangedObserver* listener);
 
   float GetBufferPercentFull() const;
 
   // Set the thread-safe notification callback. The callback can occur at any
   // time and from any thread. WARNING: It is possible for the previously set
   // callback to be called during OR AFTER a call to SetNotificationCallback.
   // Therefore, the target of the callback must either be a global function,
@@ skipping 147 matching lines @@
   const unsigned char* watch_category_;
   std::string watch_event_name_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
 }  // namespace debug
 }  // namespace base
 
 #endif  // BASE_DEBUG_TRACE_EVENT_IMPL_H_