Add a chrome://webapks page.

components/webapks_ui/webapks_ui_constants.h

+// Copyright 2017 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 COMPONENTS_WEBAPKS_UI_WEBAPKS_UI_CONSTANTS_H_
+#define COMPONENTS_WEBAPKS_UI_WEBAPKS_UI_CONSTANTS_H_
+
+namespace webapks_ui {
+
+// Resource paths.
+// Must match the resource file names.
+extern const char kAboutWebApksCSS[];
+extern const char kWebApksJS[];
+
+// Message handlers.
+// Must match the constants used in the resource files.
+extern const char kRequestWebApksInfo[];
+extern const char kReturnWebApksInfo[];
+
+// Strings.
+// Must match the constants used in the resource files.
+extern const char kTitle[];
+extern const char kHeader[];
+extern const char kPackageName[];
+extern const char kShellApkVersion[];
+extern const char kVersionCode[];
+
+}  // namespace webapks_ui
+
+#endif  // COMPONENTS_WEBAPKS_UI_WEBAPKS_UI_CONSTANTS_H_