Bug 1918300 - Apply bug 1293212 and bug 1628961 to the uikit uriloader. r=nika

Differential Revision: https://phabricator.services.mozilla.com/D221911

uriloader/exthandler/uikit/nsMIMEInfoUIKit.h

@@ -19,7 +19,7 @@ class nsMIMEInfoUIKit final : public nsMIMEInfoImpl {
   NS_IMETHOD LaunchWithFile(nsIFile* aFile) override;
 
  protected:
-  virtual nsresult LoadUriInternal(nsIURI* aURI) override;
+  [[nodiscard]] virtual nsresult LoadUriInternal(nsIURI* aURI) override;
 #ifdef DEBUG
   virtual nsresult LaunchDefaultWithFile(nsIFile* aFile) override {
     MOZ_ASSERT_UNREACHABLE("do not call this method, use LaunchWithFile");

uriloader/exthandler/uikit/nsOSHelperAppService.h

@@ -44,11 +44,11 @@ class nsOSHelperAppService final : public nsExternalHelperAppService {
   //                     spec, a unix path or a windows path depending on the
   //                     platform
   // aFile --> an nsIFile representation of that platform application path.
-  virtual nsresult GetFileTokenForPath(const char16_t* platformAppPath,
-                                       nsIFile** aFile) override;
+  [[nodiscard]] nsresult GetFileTokenForPath(const char16_t* platformAppPath,
+                                             nsIFile** aFile) override;
 
-  nsresult OSProtocolHandlerExists(const char* aScheme,
-                                   bool* aHandlerExists) override;
+  [[nodiscard]] nsresult OSProtocolHandlerExists(const char* aScheme,
+                                                 bool* aHandlerExists) override;
 };
 
 #endif  // nsOSHelperAppService_h__