Begin adding support for tab mirroring via the MediaStream audio/video capturing

content/public/common/media_stream_request.cc

Index: content/public/common/media_stream_request.cc
diff --git a/content/public/common/media_stream_request.cc b/content/public/common/media_stream_request.cc
index c516fe26200f22b7d348f74315ae1c4f86aa7e70..33626b24f0031b18833837ac13f9e501a48eb38d 100644
--- a/content/public/common/media_stream_request.cc
+++ b/content/public/common/media_stream_request.cc
@@ -6,6 +6,16 @@
 
 namespace content {
 
+bool IsAudioMediaType(MediaStreamDeviceType type) {
+  return (type == content::MEDIA_USER_AUDIO_CAPTURE ||
+          type == content::MEDIA_TAB_AUDIO_CAPTURE);
+}
+
+bool IsVideoMediaType(MediaStreamDeviceType type) {
+  return (type == content::MEDIA_USER_VIDEO_CAPTURE ||
+          type == content::MEDIA_TAB_VIDEO_CAPTURE);
+}
+
 MediaStreamDevice::MediaStreamDevice(
     MediaStreamDeviceType type,
     const std::string& device_id,