clang/win: Let some chromium_code targets build with -Wextra.

base/win/iunknown_impl_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/win/iunknown_impl.h"
 
 #include "base/win/scoped_com_initializer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
@@ skipping 12 matching lines @@
 int TestIUnknownImplSubclass::instance_count = 0;
 
 TEST(IUnknownImplTest, IUnknownImpl) {
   ScopedCOMInitializer com_initializer;
 
   EXPECT_EQ(0, TestIUnknownImplSubclass::instance_count);
   IUnknown* u = new TestIUnknownImplSubclass();
 
   EXPECT_EQ(1, TestIUnknownImplSubclass::instance_count);
 
-  EXPECT_EQ(1, u->AddRef());
-  EXPECT_EQ(1, u->AddRef());
+  EXPECT_EQ(1u, u->AddRef());
+  EXPECT_EQ(1u, u->AddRef());
 
   IUnknown* other = NULL;
   EXPECT_EQ(E_NOINTERFACE, u->QueryInterface(
       IID_IDispatch, reinterpret_cast<void**>(&other)));
   EXPECT_EQ(S_OK, u->QueryInterface(
       IID_IUnknown, reinterpret_cast<void**>(&other)));
   other->Release();
 
-  EXPECT_EQ(1, u->Release());
-  EXPECT_EQ(0, u->Release());
+  EXPECT_EQ(1u, u->Release());
+  EXPECT_EQ(0u, u->Release());
   EXPECT_EQ(0, TestIUnknownImplSubclass::instance_count);
 }
 
 }  // namespace win
 }  // namespace base