Make WeakPtr use SequenceChecker instead of ThreadChecker

base/memory/weak_ptr_unittest.cc

 // Copyright (c) 2012 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/memory/weak_ptr.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 119 matching lines @@
     delete object;
     completion->Signal();
   }
 
   static void DoDeleteArrow(Arrow* object, WaitableEvent* completion) {
     delete object;
     completion->Signal();
   }
 };
 
-}  // namespace
-
 TEST(WeakPtrFactoryTest, Basic) {
   int data;
   WeakPtrFactory<int> factory(&data);
   WeakPtr<int> ptr = factory.GetWeakPtr();
   EXPECT_EQ(&data, ptr.get());
 }
 
 TEST(WeakPtrFactoryTest, Comparison) {
   int data;
   WeakPtrFactory<int> factory(&data);
@@ skipping 315 matching lines @@
   arrow.target = target->AsWeakPtr();
 
   // Background thread tries to delete target, which violates thread ownership.
   BackgroundThread background;
   background.Start();
   ASSERT_DEATH(background.DeleteTarget(target.release()), "");
 }
 
 #endif
 
+}  // namespace
+
 }  // namespace base