Restore aura support from Mojo repo.

mandoline/ui/BUILD.gn

Index: mandoline/ui/BUILD.gn
diff --git a/device/bluetooth/uribeacon/BUILD.gn b/mandoline/ui/BUILD.gn
similarity index 64%
copy from device/bluetooth/uribeacon/BUILD.gn
copy to mandoline/ui/BUILD.gn
index 484e27270327646f886047b1d4d39d1a2e6641f1..ea281d32775628ebab4afd7537852bc8d9f20b97 100644
--- a/device/bluetooth/uribeacon/BUILD.gn
+++ b/mandoline/ui/BUILD.gn
@@ -2,12 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("uribeacon") {
-  sources = [
-    "uri_encoder.cc",
-    "uri_encoder.h",
-  ]
+import("//third_party/mojo/src/mojo/public/mojo.gni")
+
+group("ui") {
   deps = [
-    "//base",
+    "//mandoline/ui/aura",
   ]
 }