Remove unnecessary class forward declaration for usb/bluetooth_chooser_bubble_delegate.h

chrome/browser/usb/usb_chooser_bubble_delegate.h

 // Copyright 2015 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.
 
 #ifndef CHROME_BROWSER_USB_USB_CHOOSER_BUBBLE_DELEGATE_H_
 #define CHROME_BROWSER_USB_USB_CHOOSER_BUBBLE_DELEGATE_H_
 
 #include <utility>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/scoped_observer.h"
 #include "chrome/browser/ui/website_settings/chooser_bubble_delegate.h"
 #include "components/bubble/bubble_reference.h"
 #include "components/webusb/public/interfaces/webusb_permission_bubble.mojom.h"
 #include "device/usb/usb_service.h"
 #include "mojo/public/cpp/bindings/array.h"
 
 namespace content {
 class RenderFrameHost;
 }
 
 namespace device {
 class UsbDevice;
 class UsbDeviceFilter;
 }
 
-class Browser;
-
 // UsbChooserBubbleDelegate creates a chooser bubble for WebUsb.
 class UsbChooserBubbleDelegate : public ChooserBubbleDelegate,
                                  public device::UsbService::Observer {
  public:
   UsbChooserBubbleDelegate(
       content::RenderFrameHost* owner,
       mojo::Array<device::usb::DeviceFilterPtr> device_filters,
       content::RenderFrameHost* render_frame_host,
       const webusb::WebUsbPermissionBubble::GetPermissionCallback& callback);
   ~UsbChooserBubbleDelegate() override;
@@ skipping 24 matching lines @@
   // Each pair is a (device, device name).
   std::vector<std::pair<scoped_refptr<device::UsbDevice>, base::string16>>
       devices_;
   BubbleReference bubble_controller_;
   base::WeakPtrFactory<UsbChooserBubbleDelegate> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbChooserBubbleDelegate);
 };
 
 #endif  // CHROME_BROWSER_USB_USB_CHOOSER_BUBBLE_DELEGATE_H_