Bug 1727271: part 1) Simplify and document `nsContentPermissionUtils::ConvertArrayToPermissionRequest`. r=edgar

Differential Revision: https://phabricator.services.mozilla.com/D123428

dom/base/nsContentPermissionHelper.cpp

@@ -170,7 +170,7 @@ uint32_t nsContentPermissionUtils::ConvertPermissionRequestToArray(
 }
 
 /* static */
-uint32_t nsContentPermissionUtils::ConvertArrayToPermissionRequest(
+void nsContentPermissionUtils::ConvertArrayToPermissionRequest(
     nsIArray* aSrcArray, nsTArray<PermissionRequest>& aDesArray) {
   uint32_t len = 0;
   aSrcArray->GetLength(&len);
@@ -198,7 +198,6 @@ uint32_t nsContentPermissionUtils::ConvertArrayToPermissionRequest(
 
     aDesArray.AppendElement(PermissionRequest(type, options));
   }
-  return len;
 }
 
 static std::map<PContentPermissionRequestParent*, TabId>&

dom/base/nsContentPermissionHelper.h

@@ -60,7 +60,11 @@ class nsContentPermissionUtils {
   static uint32_t ConvertPermissionRequestToArray(
       nsTArray<PermissionRequest>& aSrcArray, nsIMutableArray* aDesArray);
 
-  static uint32_t ConvertArrayToPermissionRequest(
+  // Converts blindly, that is, strings are not matched against any list.
+  //
+  // @param aSrcArray needs to contain elements of type
+  // `nsIContentPermissionType`.
+  static void ConvertArrayToPermissionRequest(
       nsIArray* aSrcArray, nsTArray<PermissionRequest>& aDesArray);
 
   static nsresult CreatePermissionArray(const nsACString& aType,