Bug 1838415 - Introduce RFPTarget::MediaError. r=tjr

Differential Revision: https://phabricator.services.mozilla.com/D181243

dom/html/MediaError.cpp

@@ -68,7 +68,7 @@ void MediaError::GetMessage(nsAString& aResult) const {
     }
 
     if (!nsContentUtils::IsCallerChrome() &&
-        ownerDoc->ShouldResistFingerprinting(RFPTarget::Unknown)) {
+        ownerDoc->ShouldResistFingerprinting(RFPTarget::MediaError)) {
       aResult.Truncate();
       return;
     }

toolkit/components/resistfingerprinting/RFPTargets.inc

@@ -70,6 +70,7 @@ ITEM_VALUE(FrameRate,                   1llu << 45)
 ITEM_VALUE(RoundWindowSize,             1llu << 46)
 ITEM_VALUE(UseStandinsForNativeColors,  1llu << 47)
 ITEM_VALUE(AudioContext,                1llu << 48)
+ITEM_VALUE(MediaError,                  1llu << 49)
 
 // !!! Don't forget to update kDefaultFingerintingProtections in nsRFPService.cpp
 // if necessary.