Added Semantic header support on Android. (flutter#13262)

Added Semantic header support on Android.

Author: darrenaustin

shell/platform/android/io/flutter/view/AccessibilityBridge.java

@@ -4,6 +4,7 @@
 
 package io.flutter.view;
 
+import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.content.ContentResolver;
 import android.database.ContentObserver;
@@ -489,6 +490,8 @@ private boolean shouldSetCollectionInfo(final SemanticsNode semanticsNode) {
      */
     @Override
     @SuppressWarnings("deprecation")
+    // Supressing Lint warning for new API, as we are version guarding all calls to newer APIs
+    @SuppressLint("NewApi")
     public AccessibilityNodeInfo createAccessibilityNodeInfo(int virtualViewId) {
         if (virtualViewId >= MIN_ENGINE_GENERATED_NODE_ID) {
             // The node is in the engine generated range, and is provided by the accessibility view embedder.
@@ -753,6 +756,11 @@ public AccessibilityNodeInfo createAccessibilityNodeInfo(int virtualViewId) {
 
         result.setSelected(semanticsNode.hasFlag(Flag.IS_SELECTED));
 
+        // Heading support
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
+            result.setHeading(semanticsNode.hasFlag(Flag.IS_HEADER));
+        }
+
         // Accessibility Focus
         if (accessibilityFocusedSemanticsNode != null && accessibilityFocusedSemanticsNode.id == virtualViewId) {
             result.addAction(AccessibilityNodeInfo.ACTION_CLEAR_ACCESSIBILITY_FOCUS);