Cleanup: Remove unneeded browser_thread.h includes.

chrome/browser/usb/usb_context.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_context.h"
 
 #include "base/logging.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
-#include "content/public/browser/browser_thread.h"
 #include "third_party/libusb/src/libusb/interrupt.h"
 #include "third_party/libusb/src/libusb/libusb.h"
 
 // The UsbEventHandler works around a design flaw in the libusb interface. There
 // is currently no way to signal to libusb that any caller into one of the event
 // handler calls should return without handling any events.
 class UsbContext::UsbEventHandler : public base::PlatformThread::Delegate {
  public:
   explicit UsbEventHandler(libusb_context* context);
   virtual ~UsbEventHandler();
@@ skipping 44 matching lines @@
   event_handler_ = new UsbEventHandler(context_);
 }
 
 UsbContext::~UsbContext() {
   // destruction of UsbEventHandler is a blocking operation.
   DCHECK(thread_checker_.CalledOnValidThread());
   delete event_handler_;
   event_handler_ = NULL;
   libusb_exit(context_);
 }