Adds the audio history and always on hotwording settings.

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 96a76c0a5f4a221366438407e1399b81f24c2891..82e55106d6179e1844cf8a1482ea68cc3179a7be 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1778,6 +1778,10 @@ const char kVideoCaptureAllowedUrls[] = "hardware.video_capture_allowed_urls";
 // trigger.
 const char kHotwordSearchEnabled[] = "hotword.search_enabled_2";
 
+// A boolean pref that controls the enabled-state of hotword search voice
+// trigger from any screen.
+const char kHotwordAlwaysOnSearchEnabled[] = "hotword.always_on_search_enabled";
+
 // A boolean pref that controls whether the sound of "Ok, Google" plus a few
 // seconds of audio data before is sent back to improve voice search.
 const char kHotwordAudioLoggingEnabled[] = "hotword.audio_logging_enabled";