Prevent scrolling with TalkBack if scrolling is disabled in JS

Summary:
Right now you can scroll a horizontal ScrollView with TalkBack even if you've disabled scrolling in JS, because our HorizontalScrollView component doesn't prevent the accessibility scroll event (this doesn't seem to happen with vertical ScrollViews for some reason...) This diff adds an accessibility delegate to both of the Android ScrollView components to make sure they're not scrollable if scrolling has been disabled in JS.

Changelog: [Internal]

Reviewed By: shergin

Differential Revision: D23582689

fbshipit-source-id: b670bdb462ab9c963c7125597d60ca97c7d88a9c

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactHorizontalScrollView.java

@@ -21,11 +21,14 @@ import android.view.FocusFinder;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
 import android.view.View;
+import android.view.accessibility.AccessibilityEvent;
 import android.widget.HorizontalScrollView;
 import android.widget.OverScroller;
 import androidx.annotation.Nullable;
 import androidx.core.text.TextUtilsCompat;
+import androidx.core.view.AccessibilityDelegateCompat;
 import androidx.core.view.ViewCompat;
+import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;
 import com.facebook.common.logging.FLog;
 import com.facebook.infer.annotation.Assertions;
 import com.facebook.react.bridge.WritableMap;
@@ -104,6 +107,23 @@ public class ReactHorizontalScrollView extends HorizontalScrollView
     mReactBackgroundManager = new ReactViewBackgroundManager(this);
     mFpsListener = fpsListener;
 
+    ViewCompat.setAccessibilityDelegate(
+        this,
+        new AccessibilityDelegateCompat() {
+          @Override
+          public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) {
+            super.onInitializeAccessibilityEvent(host, event);
+            event.setScrollable(mScrollEnabled);
+          }
+
+          @Override
+          public void onInitializeAccessibilityNodeInfo(
+              View host, AccessibilityNodeInfoCompat info) {
+            super.onInitializeAccessibilityNodeInfo(host, info);
+            info.setScrollable(mScrollEnabled);
+          }
+        });
+
     mScroller = getOverScrollerFromParent();
   }