Remove MessageLoop destruction observer from //device/usb

device/usb/usb_device_handle_android.cc

Index: device/usb/usb_device_handle_android.cc
diff --git a/device/usb/usb_device_handle_android.cc b/device/usb/usb_device_handle_android.cc
index e2e0dc03d8916f15dced5183d73b0d485be5a23f..d5dce7a8e0f842d6e7029ac7a023fa108613183d 100644
--- a/device/usb/usb_device_handle_android.cc
+++ b/device/usb/usb_device_handle_android.cc
@@ -21,6 +21,8 @@ scoped_refptr<UsbDeviceHandleAndroid> UsbDeviceHandleAndroid::Create(
     const base::android::JavaRef<jobject>& usb_connection) {
   ScopedJavaLocalRef<jobject> wrapper =
       Java_ChromeUsbConnection_create(env, usb_connection);
+  // C++ doesn't own this file descriptor so CloseBlocking() is overridden
+  // below to release it without closing it.
   base::ScopedFD fd(Java_ChromeUsbConnection_getFileDescriptor(env, wrapper));
   return make_scoped_refptr(new UsbDeviceHandleAndroid(
       device, std::move(fd), blocking_task_runner, wrapper));