Allow for pausing background tabs on desktop via about:flags.

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 2923 matching lines @@
 
 #if defined(OS_CHROMEOS) || defined(OS_LINUX) || defined(OS_MACOSX) || \
     defined(OS_WIN)
 
 // Name of the flag that enables receiving entity suggestions.
 extern const char kOmniboxEntitySuggestionsName[];
 
 // Description of the flag that enables entity suggestions.
 extern const char kOmniboxEntitySuggestionsDescription[];
 
+extern const char kPauseBackgroundTabsName[];
+extern const char kPauseBackgroundTabsDescription[];
+
 #endif  // defined(OS_CHROMEOS) || defined(OS_LINUX) || defined(OS_MACOSX) ||
         // defined(OS_WIN)
 
 #if defined(OS_CHROMEOS)
 
 // Name of the flag that enables ChromeVox support for ARC.
 extern const char kEnableChromevoxArcSupportName[];
 
 // Description of the flag that enables ChromeVox support for ARC.
 extern const char kEnableChromevoxArcSupportDescription[];
@@ skipping 204 matching lines @@
 
 // Description of the about: flag enabling emoji, handwriting and voice input on
 // opt-in IME menu.
 extern const char kEnableEhvInputDescription[];
 
 #endif  // #if defined(OS_CHROMEOS)
 
 }  // namespace flag_descriptions
 
 #endif  // CHROME_BROWSER_FLAG_DESCRIPTIONS_H_