base: Cleanup class/struct forward declarations

base/trace_event/trace_event_synthetic_delay.h

 // Copyright 2014 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.
 
 // The synthetic delay framework makes it possible to dynamically inject
 // arbitrary delays into into different parts of the codebase. This can be used,
 // for instance, for testing various task scheduling algorithms.
 //
 // The delays are specified in terms of a target duration for a given block of
 // code. If the code executes faster than the duration, the thread is made to
@@ skipping 44 matching lines @@
 
 // End a named delay. The delay is applied only if this call matches the
 // first corresponding call to TRACE_EVENT_SYNTHETIC_DELAY_BEGIN with the
 // same delay.
 #define TRACE_EVENT_SYNTHETIC_DELAY_END(name)                         \
   do {                                                                \
     static base::subtle::AtomicWord impl_ptr = 0;                     \
     trace_event_internal::GetOrCreateDelay(name, &impl_ptr)->End();   \
   } while (false)
 
-template <typename Type>
-struct DefaultSingletonTraits;
-
 namespace base {
 namespace trace_event {
 
 // Time source for computing delay durations. Used for testing.
 class TRACE_EVENT_API_CLASS_EXPORT TraceEventSyntheticDelayClock {
  public:
   TraceEventSyntheticDelayClock();
   virtual ~TraceEventSyntheticDelayClock();
   virtual base::TimeTicks Now() = 0;
 
@@ skipping 80 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ScopedSyntheticDelay);
 };
 
 // Helper for registering delays. Do not use directly.
 TRACE_EVENT_API_CLASS_EXPORT base::trace_event::TraceEventSyntheticDelay*
     GetOrCreateDelay(const char* name, base::subtle::AtomicWord* impl_ptr);
 
 }  // namespace trace_event_internal
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_SYNTHETIC_DELAY_H_