Add BackgroundModeOptimizer that can restart the browser

chrome/common/pref_names.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.
 
 // Constants for the names of various preferences, for easier changing.
 
 #ifndef CHROME_COMMON_PREF_NAMES_H_
 #define CHROME_COMMON_PREF_NAMES_H_
 
 #include <stddef.h>
@@ skipping 772 matching lines @@
 
 extern const char kEasyUnlockDeviceId[];
 extern const char kEasyUnlockHardlockState[];
 extern const char kEasyUnlockLocalStateTpmKeys[];
 extern const char kEasyUnlockLocalStateUserPrefs[];
 
 extern const char kRecoveryComponentNeedsElevation[];
 
 extern const char kRegisteredSupervisedUserWhitelists[];
 
+#if BUILDFLAG(ENABLE_BACKGROUND)
+extern const char kRestartInBackground[];
+#endif
+
 #if defined(ENABLE_EXTENSIONS)
 extern const char kAnimationPolicy[];
 #endif
 
 extern const char kBackgroundTracingLastUpload[];
 
 extern const char kAllowDinosaurEasterEgg[];
 
 #if defined(OS_ANDROID)
 extern const char kClickedUpdateMenuItem[];
 extern const char kLatestVersionWhenClickedUpdateMenuItem[];
 #endif
 
 #if defined(ENABLE_MEDIA_ROUTER)
 #if defined(GOOGLE_CHROME_BUILD)
 extern const char kMediaRouterCloudServicesPrefSet[];
 extern const char kMediaRouterEnableCloudServices[];
 #endif  // defined(GOOGLE_CHROME_BUILD)
 extern const char kMediaRouterFirstRunFlowAcknowledged[];
 #endif
 
 extern const char kOriginTrialPublicKey[];
 extern const char kOriginTrialDisabledFeatures[];
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_