Added BASE_EXPORT to EnabledStateObserver class

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 <stack>
 #include <string>
 #include <vector>
 
 #include "base/atomicops.h"
+#include "base/base_export.h"
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_vector.h"
 #include "base/observer_list.h"
 #include "base/strings/string_util.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread.h"
@@ skipping 462 matching lines @@
 
 #if defined(OS_ANDROID)
   void StartATrace();
   void StopATrace();
   void AddClockSyncMetadataEvent();
 #endif
 
   // Enabled state listeners give a callback when tracing is enabled or
   // disabled. This can be used to tie into other library's tracing systems
   // on-demand.
-  class EnabledStateObserver {
+  class BASE_EXPORT EnabledStateObserver {
    public:
     // Called just after the tracing system becomes enabled, outside of the
     // |lock_|. TraceLog::IsEnabled() is true at this point.
     virtual void OnTraceLogEnabled() = 0;
 
     // Called just after the tracing system disables, outside of the |lock_|.
     // TraceLog::IsEnabled() is false at this point.
     virtual void OnTraceLogDisabled() = 0;
   };
   void AddEnabledStateObserver(EnabledStateObserver* listener);
@@ skipping 304 matching lines @@
   scoped_refptr<MessageLoopProxy> flush_message_loop_proxy_;
   subtle::AtomicWord generation_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
 }  // namespace debug
 }  // namespace base
 
 #endif  // BASE_DEBUG_TRACE_EVENT_IMPL_H_