[usb_gadget p12] Basic tests of usb_service using the USB test gadget.

components/usb_service/usb_service_impl.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 "components/usb_service/usb_service.h"
 
 #include <map>
 #include <set>
 
 #include "base/lazy_instance.h"
@@ skipping 136 matching lines @@
     // UsbDevice will be destroyed after this. The corresponding
     // PlatformUsbDevice will be unref'ed during this process.
     devices_.erase(disconnected_devices[i]);
   }
 
   libusb_free_device_list(platform_devices, true);
 }
 
 // static
 UsbService* UsbService::GetInstance() {
-  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
   UsbService* instance = g_usb_service_instance.Get().get();
   if (!instance) {
     PlatformUsbContext context = NULL;
 
     const int rv = libusb_init(&context);
     if (rv != LIBUSB_SUCCESS) {
       VLOG(1) << "Failed to initialize libusb: " << ConvertErrorToString(rv);
       return NULL;
     }
     if (!context)
       return NULL;
 
     instance = new UsbServiceImpl(context);
     g_usb_service_instance.Get().reset(instance);
   }
   return instance;
 }
 
 // static
 void UsbService::SetInstanceForTest(UsbService* instance) {
-  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
   g_usb_service_instance.Get().reset(instance);
 }
 
 }  // namespace usb_service