Add a new audio constraint, 'googHotword', that requests the hotword input

content/common/media/media_stream_options.h

Index: content/common/media/media_stream_options.h
diff --git a/content/common/media/media_stream_options.h b/content/common/media/media_stream_options.h
index e58f137000364a1a704f24bbf6328df65c31cb66..9f208da80e3cc442a890cf06186c6339046cd249 100644
--- a/content/common/media/media_stream_options.h
+++ b/content/common/media/media_stream_options.h
@@ -31,6 +31,10 @@ CONTENT_EXPORT extern const char kMediaStreamRenderToAssociatedSink[];
 // Controls whether ducking of audio is enabled on platforms that support it.
 CONTENT_EXPORT extern const char kMediaStreamAudioDucking[];
 
+// Controls whether the hotword audio stream is used on platforms that support
+// it.
+CONTENT_EXPORT extern const char kMediaStreamAudioHotword[];
+
 // StreamOptions is a Chromium representation of constraints
 // used in WebUserMediaRequest.
 // It describes properties requested by JS in a request for a new