Spec compliant video constraints for getUserMedia behind flag.

content/public/common/content_features.cc

Index: content/public/common/content_features.cc
diff --git a/content/public/common/content_features.cc b/content/public/common/content_features.cc
index cc61746a5b7c13aa475ed4322af5a521968cbdd9..0843c898db49e14dc81044c93616871d77c99a89 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -113,6 +113,10 @@ const base::Feature kMediaDocumentDownloadButton{
     base::FEATURE_DISABLED_BY_DEFAULT
 };
 
+// Enables the old algorithm for processing video constraints in getUserMedia().
+const base::Feature kMediaStreamOldVideoConstraints{
+    "MediaStreamOldVideoConstraints", base::FEATURE_ENABLED_BY_DEFAULT};
+
 // Enables the memory coordinator.
 // WARNING:
 // The memory coordinator is not ready for use and enabling this may cause