mac: Prepare for -Wunused-functions.

chrome/browser/usb/usb_device.cc

 // Copyright 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 "chrome/browser/usb/usb_device.h"
 
 #include <algorithm>
 
 #include "base/stl_util.h"
 #include "chrome/browser/usb/usb_context.h"
 #include "chrome/browser/usb/usb_device_handle.h"
 #include "content/public/browser/browser_thread.h"
 #include "third_party/libusb/src/libusb/libusb.h"
 
 #if defined(OS_CHROMEOS)
 #include "base/sys_info.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/permission_broker_client.h"
 #endif  // defined(OS_CHROMEOS)
 
 using content::BrowserThread;
 
 namespace {
 
+#if defined(OS_CHROMEOS)
 void OnRequestUsbAccessReplied(
     const base::Callback<void(bool success)>& callback,
     bool success) {
   BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
                           base::Bind(callback, success));
 }
+#endif  // defined(OS_CHROMEOS)
 
 }  // namespace
 
 UsbDevice::UsbDevice(
     scoped_refptr<UsbContext> context,
     PlatformUsbDevice platform_device,
     uint16 vendor_id,
     uint16 product_id,
     uint32 unique_id)
     : platform_device_(platform_device),
@@ skipping 102 matching lines @@
   DCHECK(thread_checker_.CalledOnValidThread());
   HandlesVector handles;
   swap(handles, handles_);
   for (std::vector<scoped_refptr<UsbDeviceHandle> >::iterator it =
       handles.begin();
       it != handles.end();
       ++it) {
     (*it)->InternalClose();
   }
 }