Add UMA to count the usage of sendBeacon with non-simple Content-Type

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 d5ff3f88f2627be299d8a9d214302e17dbdf0f11..300b692a6b8dcb19000a8301732364dc40fffd2c 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -141,6 +141,11 @@ const base::Feature kWebRtcEcdsaDefault {"WebRTC-EnableWebRtcEcdsa",
 // https://wicg.github.io/webusb
 const base::Feature kWebUsb{"WebUSB", base::FEATURE_ENABLED_BY_DEFAULT};
 
+// Make sendBeacon throw for a Blob with a non simple type.
+const base::Feature kSendBeaconThrowForBlobWithNonSimpleType{
+    "SendBeaconThrowForBlobWithNonSimpleType",
+    base::FEATURE_DISABLED_BY_DEFAULT};
+
 #if defined(OS_ANDROID)
 // Allow videos to autoplay without a user gesture if muted.
 const base::Feature kAutoplayMutedVideos{"AutoplayMutedVideos",