Remove the chrome flag to show/hide ARC files app in launcher.

chrome/browser/flag_descriptions.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 CHROME_BROWSER_FLAG_DESCRIPTIONS_H_
 #define CHROME_BROWSER_FLAG_DESCRIPTIONS_H_
 
 // Includes needed for macros allowing conditional compilation of some strings.
 #include "build/build_config.h"
 #include "build/buildflag.h"
@@ skipping 1320 matching lines @@
 extern const char kQuickUnlockPinName[];
 extern const char kQuickUnlockPinDescription[];
 extern const char kQuickUnlockPinSignin[];
 extern const char kQuickUnlockPinSigninDescription[];
 extern const char kQuickUnlockFingerprint[];
 extern const char kQuickUnlockFingerprintDescription[];
 
 extern const char kOfficeEditingComponentAppName[];
 extern const char kOfficeEditingComponentAppDescription[];
 
-extern const char kShowArcFilesAppName[];
-extern const char kShowArcFilesAppDescription[];
-
 extern const char kSmartVirtualKeyboardName[];
 extern const char kSmartVirtualKeyboardDescription[];
 
 extern const char kTeamDrivesName[];
 extern const char kTeamDrivesDescription[];
 
 extern const char kTetherName[];
 extern const char kTetherDescription[];
 
 extern const char kTouchscreenCalibrationName[];
@@ skipping 138 matching lines @@
 #endif  // defined(TOOLKIT_VIEWS) || defined(OS_ANDROID)
 
 // ============================================================================
 // Don't just add flags to the end, put them in the right section in
 // alphabetical order. See top instructions for more.
 // ============================================================================
 
 }  // namespace flag_descriptions
 
 #endif  // CHROME_BROWSER_FLAG_DESCRIPTIONS_H_