Implement two new policies to control muting the audio I/O.

chrome/browser/prefs/browser_prefs.cc

 // 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.
 
 #include "chrome/browser/prefs/browser_prefs.h"
 
 #include "chrome/browser/about_flags.h"
 #include "chrome/browser/accessibility/invert_bubble_prefs.h"
 #include "chrome/browser/autofill/autofill_manager.h"
 #include "chrome/browser/background/background_mode_manager.h"
@@ skipping 243 matching lines @@
   printing::StickySettings::RegisterUserPrefs(user_prefs);
 #endif
 
 #if !defined(OS_ANDROID) && !defined(OS_CHROMEOS)
   default_apps::RegisterUserPrefs(user_prefs);
 #endif
 
 #if defined(OS_CHROMEOS)
   chromeos::Preferences::RegisterUserPrefs(user_prefs);
   chromeos::ProxyConfigServiceImpl::RegisterPrefs(user_prefs);
+  chromeos::AudioHandler::RegisterUserPrefs(user_prefs);
 #endif
 
 #if defined(OS_WIN)
   NetworkProfileBubble::RegisterPrefs(user_prefs);
 #endif
 }
 
 void MigrateBrowserPrefs(Profile* profile, PrefService* local_state) {
   // Copy pref values which have been migrated to user_prefs from local_state,
   // or remove them from local_state outright, if copying is not required.
@@ skipping 55 matching lines @@
     }
     local_state->ClearPref(prefs::kLastPromptedGoogleURL);
 
     current_version |= GOOGLE_URL_TRACKER_PREFS;
     local_state->SetInteger(prefs::kMultipleProfilePrefMigration,
                             current_version);
   }
 }
 
 }  // namespace chrome