Convert device_sensors to use mojo.

device/sensors/public/interfaces/BUILD.gn

Index: device/sensors/public/interfaces/BUILD.gn
diff --git a/device/sensors/public/interfaces/BUILD.gn b/device/sensors/public/interfaces/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..f697e347919875e1268ea2608a5e6c446724ccf7
--- /dev/null
+++ b/device/sensors/public/interfaces/BUILD.gn
@@ -0,0 +1,13 @@
+# Copyright 2016 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("//mojo/public/tools/bindings/mojom.gni")
+
+mojom("interfaces") {
+  sources = [
+    "light.mojom",
+    "motion.mojom",
+    "orientation.mojom",
+  ]
+}