Bug 1903508 - Part 1: Add a GetKeyboardLayout() interface to LookAndFeel abstraction. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D215070

widget/LookAndFeel.h

@@ -555,6 +555,8 @@ class LookAndFeel {
     }
   }
 
+  static nsresult GetKeyboardLayout(nsACString& aLayout);
+
  protected:
   static void DoHandleGlobalThemeChange();
   // Set to true when ThemeChanged needs to be called on mTheme (and other

widget/nsXPLookAndFeel.cpp

@@ -1550,4 +1550,9 @@ void LookAndFeel::SetData(widget::FullLookAndFeel&& aTables) {
   nsLookAndFeel::GetInstance()->SetDataImpl(std::move(aTables));
 }
 
+// static
+nsresult LookAndFeel::GetKeyboardLayout(nsACString& aLayout) {
+  return nsLookAndFeel::GetInstance()->GetKeyboardLayoutImpl(aLayout);
+}
+
 }  // namespace mozilla

widget/nsXPLookAndFeel.h

@@ -72,6 +72,10 @@ class nsXPLookAndFeel : public mozilla::LookAndFeel {
 
   virtual void GetThemeInfo(nsACString&) {}
 
+  virtual nsresult GetKeyboardLayoutImpl(nsACString& aLayout) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
  protected:
   nsXPLookAndFeel() = default;