Bug 1882413 - Part 1: Re-enable MSIX one-click set to default (no change from backout). r=nalexander,mhughes

Backed out changeset 897f98487b4f

Differential Revision: https://phabricator.services.mozilla.com/D203068

Author: PrototypeNM1

browser/components/shell/WindowsUserChoice.cpp

@@ -284,6 +284,21 @@ UniquePtr<wchar_t[]> GetAssociationKeyPath(const wchar_t* aExt) {
   return keyPath;
 }
 
+nsresult AppendAssociationKeyPath(const wchar_t* aExt, nsString& output) {
+  if (aExt[0] == L'.') {
+    output.AppendLiteral(
+        u"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\FileExts\\");
+  } else {
+    output.AppendLiteral(
+        u"SOFTWARE\\Microsoft\\Windows\\Shell\\Associations\\UrlAssociations"
+        u"\\");
+  }
+
+  output.Append(aExt);
+
+  return NS_OK;
+}
+
 UniquePtr<wchar_t[]> GenerateUserChoiceHash(const wchar_t* aExt,
                                             const wchar_t* aUserSid,
                                             const wchar_t* aProgId,

browser/components/shell/WindowsUserChoice.h

@@ -61,6 +61,14 @@ CheckUserChoiceHashResult CheckUserChoiceHash(const wchar_t* aExt,
  */
 mozilla::UniquePtr<wchar_t[]> GetAssociationKeyPath(const wchar_t* aExt);
 
+/*
+ * Appends the registry path for the given association, file extension or
+ * protocol to the parameter string.
+ *
+ * @return The path, or nullptr on failure.
+ */
+nsresult AppendAssociationKeyPath(const wchar_t* aExt, nsString& output);
+
 /*
  * Get the current user's SID
  *