Destroy all Singletons and LazyInstances between each test.

base/memory/singleton.h

 // Copyright (c) 2011 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.
 
 // PLEASE READ: Do you really need a singleton?
 //
 // Singletons make it hard to determine the lifetime of an object, which can
 // lead to buggy code and spurious crashes.
 //
 // Instead of adding another singleton into the mix, try to identify either:
@@ skipping 98 matching lines @@
     // Only constructs once and returns pointer; otherwise returns NULL.
     if (base::subtle::NoBarrier_AtomicExchange(&dead_, 1))
       return NULL;
 
     return new(buffer_.void_data()) Type();
   }
 
   static void Delete(Type* p) {
     if (p != NULL)
       p->Type::~Type();
+
+    // Only in unittests, automatically Resurrect() the singleton so that tests
+    // do not have to manually call it. See <http://crbug.com/258047>.
+#if defined(UNIT_TEST)
+    Resurrect();
+#endif
   }
 
   static const bool kRegisterAtExit = true;
   static const bool kAllowedToAccessOnNonjoinableThread = true;
 
   // Exposed for unittesting.
   static void Resurrect() {
     base::subtle::NoBarrier_Store(&dead_, 0);
   }
 
@@ skipping 147 matching lines @@
     instance_ = 0;
   }
   static base::subtle::AtomicWord instance_;
 };
 
 template <typename Type, typename Traits, typename DifferentiatingType>
 base::subtle::AtomicWord Singleton<Type, Traits, DifferentiatingType>::
     instance_ = 0;
 
 #endif  // BASE_MEMORY_SINGLETON_H_