Fix and enable MSVC warning C4018 for base/.

base/debug/gdi_debug_util_win.cc

 // Copyright 2014 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/debug/gdi_debug_util_win.h"
 
 #include <cmath>
 
 #include <psapi.h>
 #include <TlHelp32.h>
 
@@ skipping 57 matching lines @@
   DWORD last_error = GetLastError();
 
   LONG width = header->biWidth;
   LONG heigth = header->biHeight;
 
   base::debug::Alias(&last_error);
   base::debug::Alias(&width);
   base::debug::Alias(&heigth);
   base::debug::Alias(&shared_section);
 
-  int num_user_handles = GetGuiResources(GetCurrentProcess(),
-                                         GR_USEROBJECTS);
+  DWORD num_user_handles = GetGuiResources(GetCurrentProcess(), GR_USEROBJECTS);
 
-  int num_gdi_handles = GetGuiResources(GetCurrentProcess(),
-                                        GR_GDIOBJECTS);
+  DWORD num_gdi_handles = GetGuiResources(GetCurrentProcess(), GR_GDIOBJECTS);
   if (num_gdi_handles == 0) {
     DWORD get_gui_resources_error = GetLastError();
     base::debug::Alias(&get_gui_resources_error);
     CHECK(false);
   }
 
   base::debug::Alias(&num_gdi_handles);
   base::debug::Alias(&num_user_handles);
 
   const DWORD kLotsOfHandles = 9990;
@@ skipping 22 matching lines @@
         0, &small_data, shared_section, 0);
     CHECK(small_bitmap != NULL);
     DeleteObject(small_bitmap);
   }
   // Maybe the child processes are the ones leaking GDI or USER resouces.
   CollectChildGDIUsageAndDie(GetCurrentProcessId());
 }
 
 }  // namespace debug
 }  // namespace base