[sensors] Add a browser test to sanity check ambient light sensor.

device/generic_sensor/platform_sensor_provider_default.cc

Index: device/generic_sensor/platform_sensor_provider_default.cc
diff --git a/device/generic_sensor/platform_sensor_provider_default.cc b/device/generic_sensor/platform_sensor_provider_default.cc
deleted file mode 100644
index fa0d536816f333e70539c4e16b553dc423a88634..0000000000000000000000000000000000000000
--- a/device/generic_sensor/platform_sensor_provider_default.cc
+++ /dev/null
@@ -1,14 +0,0 @@
-// 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.
-
-#include "device/generic_sensor/platform_sensor_provider.h"
-
-namespace device {
-
-// static
-PlatformSensorProvider* PlatformSensorProvider::GetInstance() {
-  return nullptr;
-}
-
-}  // namespace device