Convert --enable-md-history to a feature flag.

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_
 
+#include "base/feature_list.h"
 #include "build/build_config.h"
 
 // Don't add more switch files here. This is linked into some places like the
 // installer where dependencies should be limited. Instead, have files
 // directly include your switch file.
 
 namespace switches {
 
 // -----------------------------------------------------------------------------
 // Can't find the switch you are looking for? Try looking in
@@ skipping 94 matching lines @@
 extern const char kEnableClearBrowsingDataCounters[];
 extern const char kEnableCloudPrintProxy[];
 extern const char kEnableDevToolsExperiments[];
 extern const char kEnableDeviceDiscoveryNotifications[];
 extern const char kEnableDomainReliability[];
 extern const char kEnableExperimentalHotwordHardware[];
 extern const char kEnableExtensionActivityLogging[];
 extern const char kEnableExtensionActivityLogTesting[];
 extern const char kEnableFastUnload[];
 extern const char kEnableMaterialDesignExtensions[];
-extern const char kEnableMaterialDesignHistory[];
 extern const char kEnableMaterialDesignPolicyPage[];
 extern const char kEnableNaCl[];
 extern const char kEnableNativeNotifications[];
 extern const char kEnableNavigationTracing[];
 extern const char kEnableNetBenchmarking[];
 extern const char kEnableNewBookmarkApps[];
 extern const char kEnableNTPPopularSites[];
 extern const char kEnableNTPSearchEngineCountryDetection[];
 extern const char kEnableOfflineAutoReload[];
 extern const char kEnableOfflineAutoReloadVisibleOnly[];
@@ skipping 47 matching lines @@
 extern const char kJavaScriptHarmony[];
 extern const char kKeepAliveForTest[];
 extern const char kKioskMode[];
 extern const char kKioskModePrinting[];
 extern const char kLoadComponentExtension[];
 extern const char kLoadExtension[];
 #if !defined(GOOGLE_CHROME_BUILD)
 extern const char kLocalNtpReload[];
 #endif
 extern const char kMakeDefaultBrowser[];
+extern const base::Feature kMaterialDesignHistoryFeature;
 extern const char kMediaCacheSize[];
 extern const char kMediaRouter[];
 extern const char kMessageLoopHistogrammer[];
 extern const char kMetricsRecordingOnly[];
 extern const char kMonitoringDestinationID[];
 extern const char kNetLogCaptureMode[];
 extern const char kNoDefaultBrowserCheck[];
 extern const char kNoDisplayingInsecureContent[];
 extern const char kNoExperiments[];
 extern const char kNoFirstRun[];
@@ skipping 210 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_