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

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 360e5faeef2ee59eef2eefb2019e1cc353dc21f3..63caee2c9c236aff1f0a50757adbc3c14d68cfe7 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -494,7 +494,9 @@ const char kNetworkPredictionEnabled[] = "dns_prefetching.enabled";
 const char kDefaultAppsInstallState[] = "default_apps_install_state";
 
 #if defined(OS_CHROMEOS)
-// An integer pref to initially mute volume if 1.
+// An integer pref to initially mute volume if 1. This pref is ignored if
+// |kAudioOutputAllowed| is set to false, but its value is preserved, therefore
+// when the policy is lifted the original mute state is restored.
 const char kAudioMute[] = "settings.audio.mute";
 
 // TODO(derat): This is deprecated in favor of |kAudioVolumePercent|; remove it
@@ -1780,6 +1782,15 @@ const char kSyncSpareBootstrapToken[] = "sync.spare_bootstrap_token";
 // storage for the user.
 const char kExternalStorageDisabled[] = "hardware.external_storage_disabled";
 
+// A pref holding the value of the policy used to disable playing audio on
+// ChromeOS devices. This pref overrides |kAudioMute| but does not overwrite
+// it, therefore when the policy is lifted the original mute state is restored.
+const char kAudioOutputAllowed[] = "hardware.audio_output_enabled";
+
+// A pref holding the value of the policy used to disable capturing audio on
+// ChromeOS devices.
+const char kAudioCaptureAllowed[] = "hardware.audio_capture_enabled";
+
 // A dictionary that maps usernames to wallpaper properties.
 const char kUsersWallpaperInfo[] = "user_wallpaper_info";
 #endif