Add chooser permission UI code for Mac

content/renderer/usb/web_usb_client_impl.cc

Index: content/renderer/usb/web_usb_client_impl.cc
diff --git a/content/renderer/usb/web_usb_client_impl.cc b/content/renderer/usb/web_usb_client_impl.cc
index ef1b260bde826088176acc4e735951f1bceb2090..33d7f37fde8eff367d42f55d908bff3d8b639b4f 100644
--- a/content/renderer/usb/web_usb_client_impl.cc
+++ b/content/renderer/usb/web_usb_client_impl.cc
@@ -65,7 +65,6 @@ void OnGetDevicesComplete(
   scoped_callbacks.PassCallbacks()->onSuccess(blink::adoptWebPtr(devices));
 }
 
-#if !defined(OS_MACOSX)
 void OnRequestDevicesComplete(
     ScopedWebCallbacks<blink::WebUSBClientRequestDeviceCallbacks> callbacks,
     device::usb::DeviceManager* device_manager,
@@ -83,7 +82,6 @@ void OnRequestDevicesComplete(
         blink::adoptWebPtr<blink::WebUSBDevice>(nullptr));
   }
 }
-#endif
 
 }  // namespace
 
@@ -104,11 +102,6 @@ void WebUSBClientImpl::getDevices(
 void WebUSBClientImpl::requestDevice(
     const blink::WebUSBDeviceRequestOptions& options,
     blink::WebUSBClientRequestDeviceCallbacks* callbacks) {
-#if defined(OS_MACOSX)
-  callbacks->onError(blink::WebUSBError(blink::WebUSBError::Error::Service,
-                                        base::UTF8ToUTF16("Not implemented.")));
-  delete callbacks;
-#else
   if (!webusb_permission_bubble_) {
     service_registry_->ConnectToRemoteService(
         mojo::GetProxy(&webusb_permission_bubble_));
@@ -123,7 +116,6 @@ void WebUSBClientImpl::requestDevice(
       device_filters.Pass(),
       base::Bind(&OnRequestDevicesComplete, base::Passed(&scoped_callbacks),
                  base::Unretained(device_manager_.get())));
-#endif
 }
 
 void WebUSBClientImpl::setObserver(Observer* observer) {