base: Use nullptr instead of NULL and static_cast in discardable memory unit tests.

base/memory/discardable_memory_unittest.cc

 // Copyright (c) 2013 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/discardable_memory.h"
 
 #include <algorithm>
 
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 47 matching lines @@
                              supported_types.end(),
                              IsNativeType));
 #endif
 }
 
 // Test Lock() and Unlock() functionalities.
 TEST_P(DiscardableMemoryTest, LockAndUnLock) {
   const scoped_ptr<DiscardableMemory> memory(CreateLockedMemory(kSize));
   ASSERT_TRUE(memory);
   void* addr = memory->Memory();
-  ASSERT_NE(static_cast<void*>(NULL), addr);
+  ASSERT_NE(nullptr, addr);
 
   memory->Unlock();
 
   EXPECT_NE(DISCARDABLE_MEMORY_LOCK_STATUS_FAILED, memory->Lock());
   addr = memory->Memory();
-  ASSERT_NE(static_cast<void*>(NULL), addr);
+  ASSERT_NE(nullptr, addr);
 
   memory->Unlock();
 }
 
 // Test delete a discardable memory while it is locked.
 TEST_P(DiscardableMemoryTest, DeleteWhileLocked) {
   const scoped_ptr<DiscardableMemory> memory(CreateLockedMemory(kSize));
   ASSERT_TRUE(memory);
 }
 
@@ skipping 24 matching lines @@
   return supported_types;
 }
 
 INSTANTIATE_TEST_CASE_P(
     DiscardableMemoryTests,
     DiscardableMemoryTest,
     ::testing::ValuesIn(GetSupportedDiscardableMemoryTypes()));
 
 }  // namespace
 }  // namespace base