Build a basic Mojo service framework for device/usb

device/usb/public/cpp/BUILD.gn

Index: device/usb/public/cpp/BUILD.gn
diff --git a/mojo/util/BUILD.gn b/device/usb/public/cpp/BUILD.gn
similarity index 50%
copy from mojo/util/BUILD.gn
copy to device/usb/public/cpp/BUILD.gn
index 379bc96230e7c6037bca99a4a311de60a65c109a..43cea68e3dbdea9cc24eb578cc504673656f9242 100644
--- a/mojo/util/BUILD.gn
+++ b/device/usb/public/cpp/BUILD.gn
@@ -2,14 +2,15 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("filename_util") {
+source_set("cpp") {
   sources = [
-    "filename_util.cc",
-    "filename_util.h",
+    "device_manager_delegate.h",
+    "device_manager_factory.h",
   ]
 
-  deps = [
+  public_deps = [
     "//base",
-    "//url",
+    "//device/usb/public/interfaces",
+    "//third_party/mojo/src/mojo/public/cpp/bindings",
   ]
 }