Add a convenience typedef LazyInstance<T>::Leaky to avoid repeating T.

base/lazy_instance_unittest.cc

 // 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.
 
 #include "base/at_exit.h"
 #include "base/atomic_sequence_num.h"
 #include "base/lazy_instance.h"
 #include "base/threading/simple_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 115 matching lines @@
     static base::LazyInstance<DeleteLogger> test = LAZY_INSTANCE_INITIALIZER;
     test.Get().SetDeletedPtr(&deleted1);
   }
   EXPECT_TRUE(deleted1);
 
   // Check that using a *leaky* LazyInstance makes the dtor not run
   // when the AtExitManager finishes.
   bool deleted2 = false;
   {
     base::ShadowingAtExitManager shadow;
-    static base::LazyInstance<DeleteLogger,
-                              base::LeakyLazyInstanceTraits<DeleteLogger> >
+    static base::LazyInstance<DeleteLogger>::Leaky
         test = LAZY_INSTANCE_INITIALIZER;
     test.Get().SetDeletedPtr(&deleted2);
   }
   EXPECT_FALSE(deleted2);
 }