Make ARRAYSIZE_UNSAFE() just use arraysize().

chrome/utility/chrome_content_utility_ipc_whitelist.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 "chrome/utility/chrome_content_utility_ipc_whitelist.h"
 
 #if defined(ENABLE_EXTENSIONS)
 #include "chrome/common/extensions/chrome_utility_extensions_messages.h"
 #endif
 
+#if defined(ENABLE_EXTENSIONS)
 const uint32 kMessageWhitelist[] = {
-#if defined(ENABLE_EXTENSIONS)
 #if defined(OS_WIN)
     ChromeUtilityHostMsg_GetWiFiCredentials::ID,
 #endif  // defined(OS_WIN)
     ChromeUtilityMsg_ImageWriter_Cancel::ID,
     ChromeUtilityMsg_ImageWriter_Write::ID,
     ChromeUtilityMsg_ImageWriter_Verify::ID
+};
+const size_t kMessageWhitelistSize = arraysize(kMessageWhitelist);
+#else
+// Note: Zero-size arrays are not valid C++.
+const uint32 kMessageWhitelist[] = { 0 };
+const size_t kMessageWhitelistSize = 0;

[Tom Sepez, 2014/10/13 23:07:12]

Alternatively, It looks like this is used only in one place in
chrome_content_utility_client, right after a ENABLE_EXTENSIONS ifdef, as it
turns out.  Maybe that usage gets guarded as well, and this just doesn't exist
unless ENABLE_EXTENSIONS.

 #endif  // defined(ENABLE_EXTENSIONS)
-};
-
-const size_t kMessageWhitelistSize = ARRAYSIZE_UNSAFE(kMessageWhitelist);