Remove kDisableDownloadNotification and stop compiling shelf code on

chrome/common/chrome_switches.h

 // Copyright (c) 2012 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.
 
 // Defines the shared command-line switches used by code in the Chrome
 // directory that don't have anywhere more specific to go.
 
 #ifndef CHROME_COMMON_CHROME_SWITCHES_H_
 #define CHROME_COMMON_CHROME_SWITCHES_H_
 
@@ skipping 55 matching lines @@
 extern const char kDisableBundledPpapiFlash[];
 extern const char kDisableCastStreamingHWEncoding[];
 extern const char kDisableChildAccountDetection[];
 extern const char kDisableClearBrowsingDataCounters[];
 extern const char kDisableClientSidePhishingDetection[];
 extern const char kDisableComponentExtensionsWithBackgroundPages[];
 extern const char kDisableComponentUpdate[];
 extern const char kDisableDefaultApps[];
 extern const char kDisableDeviceDiscoveryNotifications[];
 extern const char kDisableDomainReliability[];
-extern const char kDisableDownloadNotification[];
 extern const char kDisableExtensionsFileAccessCheck[];
 extern const char kDisableExtensionsHttpThrottling[];
 extern const char kDisableExtensions[];
 extern const char kDisableFieldTrialTestingConfig[];
 extern const char kDisableHttp2[];
 extern const char kDisableJavaScriptHarmonyShipping[];
 extern const char kDisableMaterialDesignDownloads[];
 extern const char kDisableMinimizeOnSecondLauncherItemClick[];
 extern const char kDisableNewBookmarkApps[];
 extern const char kDisableNTPPopularSites[];
@@ skipping 323 matching lines @@
 #if defined(ENABLE_TASK_MANAGER)
 bool NewTaskManagerEnabled();
 #endif  // defined(ENABLE_TASK_MANAGER)
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in
 // alphabetical order, or in one of the ifdefs (also in order in each section).
 
 }  // namespace switches
 
 #endif  // CHROME_COMMON_CHROME_SWITCHES_H_