Bug 1731803 - Change QM_TO_RESULT to use generic ToResult function; r=dom-storage-reviewers,jari

Differential Revision: https://phabricator.services.mozilla.com/D126271

dom/quota/QMResult.h

@@ -72,6 +72,6 @@ inline OkOrErr ToResult(QMResult&& aValue);
 // TODO: Maybe move this to mfbt/ResultExtensions.h
 #define MOZ_TO_RESULT(expr) ToResult(expr)
 
-#define QM_TO_RESULT(expr) ToResult(ToQMResult(expr))
+#define QM_TO_RESULT(expr) ToResult<QMResult>(expr)
 
 #endif

dom/quota/QMResultInlines.h

@@ -12,11 +12,11 @@
 #endif
 
 #include "mozilla/Result.h"
+#include "mozilla/ResultExtensions.h"
+
 #ifdef QM_ERROR_STACKS_ENABLED
-#  include "mozilla/ResultVariant.h"
 #  include "nsError.h"
-#else
-#  include "mozilla/ResultExtensions.h"
+#  include "mozilla/ResultVariant.h"
 #endif
 
 namespace mozilla {
@@ -55,6 +55,11 @@ class [[nodiscard]] GenericErrorResult<QMResult> {
   operator nsresult() const { return mErrorValue.NSResult(); }
 };
 
+template <>
+struct ResultTypeTraits<QMResult> {
+  static QMResult From(nsresult aValue) { return ToQMResult(aValue); }
+};
+
 inline OkOrErr ToResult(const QMResult& aValue) {
   if (NS_FAILED(aValue.NSResult())) {
     return Err(aValue);