Introduce proximity_auth component.

components/proximity_auth/BUILD.gn

Index: components/proximity_auth/BUILD.gn
diff --git a/components/proximity_auth/BUILD.gn b/components/proximity_auth/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..5058d09b9b8a36b65ec0b9fa6c11dcff5db1c90b
--- /dev/null
+++ b/components/proximity_auth/BUILD.gn
@@ -0,0 +1,24 @@
+# Copyright 2014 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.
+
+static_library("proximity_auth") {
+  sources = [
+    "proximity_auth_system.cc",
+    "proximity_auth_system.h",
+    "remote_device.h",
+  ]
+}
+
+test("proximity_auth_unittests") {
+  sources = [
+    "proximity_auth_system_unittest.cc",
+    "run_all_unittests.cc",
+  ]
+
+  deps = [
+    ":proximity_auth",
+    "//base/test:test_support",
+    "//testing/gtest",
+  ]
+}