Bug 1626036 - Cache SELECTED state in Mac. r=morgan

Differential Revision: https://phabricator.services.mozilla.com/D69133

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

accessible/mac/mozAccessible.mm

@@ -245,8 +245,8 @@ static inline NSMutableArray* ConvertToNSArray(nsTArray<ProxyAccessible*>& aArra
   NS_OBJC_END_TRY_ABORT_BLOCK_NIL;
 }
 
-static const uint64_t kCachedStates =
-    states::CHECKED | states::PRESSED | states::MIXED | states::EXPANDED | states::CURRENT;
+static const uint64_t kCachedStates = states::CHECKED | states::PRESSED | states::MIXED |
+                                      states::EXPANDED | states::CURRENT | states::SELECTED;
 static const uint64_t kCacheInitialized = ((uint64_t)0x1) << 63;
 
 - (uint64_t)state {

accessible/mac/mozSelectableElements.mm

@@ -53,28 +53,13 @@
 - (id)selectedChildren {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL;
 
-  NSMutableArray* selectedChildren = [[NSMutableArray alloc] init];
-  if (AccessibleWrap* accWrap = [self getGeckoAccessible]) {
-    AutoTArray<Accessible*, 10> selectedItems;
-    accWrap->SelectedItems(&selectedItems);
-    for (uint64_t i = 0; i < selectedItems.Length(); i++) {
-      mozAccessible* nativeChild;
-      selectedItems.ElementAt(i)->GetNativeInterface((void**)&nativeChild);
-      if (nativeChild) {
-        [selectedChildren addObject:nativeChild];
-      }
-    }
-  } else if (ProxyAccessible* proxy = [self getProxyAccessible]) {
-    AutoTArray<ProxyAccessible*, 10> selectedItems;
-    proxy->SelectedItems(&selectedItems);
-    for (uint64_t i = 0; i < selectedItems.Length(); i++) {
-      if (mozAccessible* nativeChild = GetNativeFromProxy(selectedItems.ElementAt(i))) {
-        [selectedChildren addObject:nativeChild];
-      }
-    }
-  }
-
-  return selectedChildren;
+  return [[self children]
+      filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(mozAccessible* child,
+                                                                        NSDictionary* bindings) {
+        // Return mozSelectableChildAccessibles that have are selected (truthy value).
+        return
+            [child isKindOfClass:[mozSelectableChildAccessible class]] && [[child value] boolValue];
+      }]];
 
   NS_OBJC_END_TRY_ABORT_BLOCK_NIL;
 }
@@ -90,6 +75,7 @@
 @implementation mozSelectableChildAccessible
 
 - (id)value {
+  // Retuens true if item is selected.
   return [NSNumber numberWithBool:[self stateWithMask:states::SELECTED] != 0];
 }