Reland: Introduce the devices Mojo app

device/usb/public/interfaces/BUILD.gn

Index: device/usb/public/interfaces/BUILD.gn
diff --git a/device/usb/public/interfaces/BUILD.gn b/device/usb/public/interfaces/BUILD.gn
deleted file mode 100644
index 14b93625005689164e8e5335ecee5a916866ddf0..0000000000000000000000000000000000000000
--- a/device/usb/public/interfaces/BUILD.gn
+++ /dev/null
@@ -1,12 +0,0 @@
-# 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.
-
-import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
-
-mojom("interfaces") {
-  sources = [
-    "device.mojom",
-    "device_manager.mojom",
-  ]
-}