Isolate tests by running AtExit callbacks between them.

base/lazy_instance.h

 // Copyright (c) 2008 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 LazyInstance<Type, Traits> class manages a single instance of Type,
 // which will be lazily created on the first time it's accessed.  This class is
 // useful for places you would normally use a function-level static, but you
 // need to have guaranteed thread-safety.  The Type constructor will only ever
 // be called once, even if two threads are racing to create the object.  Get()
 // and Pointer() will always return the same, completely initialized instance.
@@ skipping 58 matching lines @@
   // static initializer to register the empty destructor with atexit().
 
   // Make sure that instance is created, creating or waiting for it to be
   // created if neccessary.  Constructs with |ctor| in the space provided by
   // |instance| and registers dtor for destruction at program exit.
   void EnsureInstance(void* instance, void (*ctor)(void*), void (*dtor)(void*));
 
   base::subtle::Atomic32 state_;
 
  private:
+  // Resets state of |helper| to STATE_EMPTY so that it can be reused.
+  // Not thread safe.
+  static void ResetState(void* helper);
+
   DISALLOW_COPY_AND_ASSIGN(LazyInstanceHelper);
 };
 
 template <typename Type, typename Traits = DefaultLazyInstanceTraits<Type> >
 class LazyInstance : public LazyInstanceHelper {
  public:
   explicit LazyInstance(LinkerInitialized x) : LazyInstanceHelper(x) { }
   // Declaring a destructor (even if it's empty) will cause MSVC to register a
   // static initializer to register the empty destructor with atexit().
 
@@ skipping 21 matching lines @@
 
  private:
   int8 buf_[sizeof(Type)];  // Preallocate the space for the Type instance.
 
   DISALLOW_COPY_AND_ASSIGN(LazyInstance);
 };
 
 }  // namespace base
 
 #endif  // BASE_LAZY_INSTANCE_H_