Remove the code added to make extensions compile on Aura Android.

extensions/browser/api/serial/serial_api.cc

Index: extensions/browser/api/serial/serial_api.cc
diff --git a/extensions/browser/api/serial/serial_api.cc b/extensions/browser/api/serial/serial_api.cc
index d80008e497d91fc7d289bb9032c7f9103585c927..0d477be738711951f7048f306f2fc8c27697471b 100644
--- a/extensions/browser/api/serial/serial_api.cc
+++ b/extensions/browser/api/serial/serial_api.cc
@@ -86,14 +86,11 @@ bool SerialGetDevicesFunction::Prepare() {
 void SerialGetDevicesFunction::Work() {
   DCHECK_CURRENTLY_ON(BrowserThread::FILE);
 
-// TODO(moshayedi): crbug.com/549257. Add USB support for Aura on Android.
-#if !defined(OS_ANDROID)
   scoped_ptr<device::SerialDeviceEnumerator> enumerator =
       device::SerialDeviceEnumerator::Create();
   mojo::Array<device::serial::DeviceInfoPtr> devices = enumerator->GetDevices();
   results_ = serial::GetDevices::Results::Create(
       devices.To<std::vector<linked_ptr<serial::DeviceInfo> > >());
-#endif
 }
 
 SerialConnectFunction::SerialConnectFunction() {