Destroy all Singletons and LazyInstances between each test.

base/memory/singleton.h

Index: base/memory/singleton.h
diff --git a/base/memory/singleton.h b/base/memory/singleton.h
index 0d4fc8990c443f3b025c37a5937bf232ca4ac14d..28fda3d22e4b86589aa036efae500bfea200e675 100644
--- a/base/memory/singleton.h
+++ b/base/memory/singleton.h
@@ -116,6 +116,12 @@ struct StaticMemorySingletonTraits {
   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;