[Lacros] Rename /chromeos/features/ to /chromes/constants/

To support Bluetooth APIs in Lacros, we will need to make some code in
/ash/constants/ common to both Ash and Lacros. Among these are constants
in ash_features.{cc.h} that can move to chromeos_features.{cc.h}.
The latter files were recently added in /chormeos/features/. For
symmetry, this CL renames subdir "features" to "constants".

Bug: 1229787
Change-Id: Ia08f29dec6f9f49e1a7ca2253db315505ede3206
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3262090
Reviewed-by: James Cook <jamescook@chromium.org>
Reviewed-by: Jenny Zhang <jennyz@chromium.org>
Reviewed-by: Evan Liu <evliu@google.com>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/main@{#939461}

diff --git a/chromeos/constants/chromeos_features.h b/chromeos/constants/chromeos_features.h
new file mode 100644
index 0000000..e6e2086
--- /dev/null
+++ b/chromeos/constants/chromeos_features.h

@@ -0,0 +1,19 @@
+// Copyright 2021 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.
+
+#ifndef CHROMEOS_CONSTANTS_CHROMEOS_FEATURES_H_
+#define CHROMEOS_CONSTANTS_CHROMEOS_FEATURES_H_
+
+#include "base/feature_list.h"
+
+// This file is only for the feature flags that are shared between ash-chrome
+// and lacros-chrome which is not common. For ash features, please add them
+// in //ash/constants/ash_features.h.
+namespace chromeos {
+
+extern const base::Feature kLacrosTtsSupport;
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_CONSTANTS_CHROMEOS_FEATURES_H_