Bug 1594300: Implement xpcAccessible::TakeFocus for ProxyAccessibles on Windows. r=yzen

1. Implement ProxyAccessible::TakeFocus on Windows.
2. Use this implementation in xpcAccessible::TakeFocus like we do on other platforms.
3. Enable accessible/tests/browser/fission/browser_take_focus.js on Windows, since it now works.

Differential Revision: https://phabricator.services.mozilla.com/D59977

--HG--
extra : moz-landing-system : lando

accessible/ipc/win/ProxyAccessible.cpp

@@ -724,5 +724,13 @@ void ProxyAccessible::DOMNodeID(nsString& aID) {
   aID = (wchar_t*)resultWrap;
 }
 
+void ProxyAccessible::TakeFocus() {
+  RefPtr<IAccessible> acc;
+  if (!GetCOMInterface((void**)getter_AddRefs(acc))) {
+    return;
+  }
+  acc->accSelect(SELFLAG_TAKEFOCUS, kChildIdSelf);
+}
+
 }  // namespace a11y
 }  // namespace mozilla

accessible/tests/browser/fission/browser.ini

@@ -12,4 +12,4 @@ support-files =
 [browser_reframe_visibility.js]
 [browser_src_change.js]
 [browser_take_focus.js]
-skip-if = fission || (os == 'win') # Bug 1556627 and 1594300 xpcAccessible::TakeFocus() is not implemented on Windows with e10s.
+skip-if = fission # Bug 1556627

accessible/xpcom/xpcAccessible.cpp

@@ -636,11 +636,7 @@ xpcAccessible::TakeFocus() {
   if (IntlGeneric().IsNull()) return NS_ERROR_FAILURE;
 
   if (ProxyAccessible* proxy = IntlGeneric().AsProxy()) {
-#if defined(XP_WIN)
-    return NS_ERROR_NOT_IMPLEMENTED;
-#else
     proxy->TakeFocus();
-#endif
   } else {
     Intl()->TakeFocus();
   }