Fix default accessibility delegate

Summary:
The current accessibility implementation tries to generalize every view's accessibility node info by setting an accessibility delegate on every view -- regardless of whether or not any accessibility properties are set. This delegate however doesn't correctly set the appropriate accessibility node fields for every view. For example, ScrollViews needs AccessibilityNode.setScrollable(true) set, but the generic delegate does not account for this. For now let's avoid unnecessarily
setting an accessibility delegate on views that don't have any accessibility props set, which will likely fix the majority of these issues.

Reviewed By: mdvacca

Differential Revision: D10138128

fbshipit-source-id: b999b41e7256e3dce94cd70e9b944979d52f74fd

ReactAndroid/src/main/java/com/facebook/react/uimanager/AccessibilityDelegateUtil.java

@@ -67,21 +67,20 @@ private AccessibilityDelegateUtil() {
   }
 
   public static void setDelegate(final View view) {
+    final String accessibilityHint = (String) view.getTag(R.id.accessibility_hint);
+    final AccessibilityRole accessibilityRole = (AccessibilityRole) view.getTag(R.id.accessibility_role);
     // if a view already has an accessibility delegate, replacing it could cause problems,
     // so leave it alone.
-    if (!ViewCompat.hasAccessibilityDelegate(view)) {
+    if (!ViewCompat.hasAccessibilityDelegate(view) &&
+      accessibilityHint != null &&
+      accessibilityRole != null) { 
       ViewCompat.setAccessibilityDelegate(
         view,
         new AccessibilityDelegateCompat() {
           @Override
           public void onInitializeAccessibilityNodeInfo(
             View host, AccessibilityNodeInfoCompat info) {
             super.onInitializeAccessibilityNodeInfo(host, info);
-            String accessibilityHint = (String) view.getTag(R.id.accessibility_hint);
-            AccessibilityRole accessibilityRole = (AccessibilityRole) view.getTag(R.id.accessibility_role);
-            if (accessibilityRole == null) {
-              accessibilityRole = AccessibilityRole.NONE;
-            }
             setRole(info, accessibilityRole, view.getContext());
             if (!(accessibilityHint == null)) {
               String contentDescription=(String)info.getContentDescription();
@@ -103,7 +102,10 @@ public void onInitializeAccessibilityNodeInfo(
 
   //TODO: Eventually support for other languages on talkback
 
-  public static void setRole(AccessibilityNodeInfoCompat nodeInfo, final AccessibilityRole role, final Context context) {
+  public static void setRole(AccessibilityNodeInfoCompat nodeInfo, AccessibilityRole role, final Context context) {
+    if (role == null) {
+      role = AccessibilityRole.NONE;
+    }
     nodeInfo.setClassName(role.getValue());
     if (Locale.getDefault().getLanguage().equals(new Locale("en").getLanguage())) {
       if (role.equals(AccessibilityRole.LINK)) {