av1 decode flag

Check if playback is allowed with:
base::FeatureList::IsEnabled(media::kAv1Decoder);

BUG=b/69268646
[email protected]

Change-Id: Iafafba99c876b2619941f5ba1567be613513c18d
Reviewed-on: https://chromium-review.googlesource.com/767055
Reviewed-by: Brett Wilson <[email protected]>
Reviewed-by: Dale Curtis <[email protected]>
Commit-Queue: Johann Koenig <[email protected]>
Cr-Commit-Position: refs/heads/master@{#516916}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 249a34e..e2206ab 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -61,6 +61,10 @@
 const char kAutoplayPolicyDocumentUserActivation[] =
     "Document user activation is required.";
 
+extern const char kAv1DecoderName[] = "Enable AV1 video decoding.";
+extern const char kAv1DecoderDescription[] =
+    "Allow decoding of files with the AV1 video codec.";
+
 const char kBackgroundVideoTrackOptimizationName[] =
     "Optimize background video playback.";
 const char kBackgroundVideoTrackOptimizationDescription[] =