Release the AccessibilityBridge when destroying a legacy FlutterView (flutter#20610)

Author: jason-simmons

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

@@ -434,6 +434,7 @@ public void destroy() {
     if (!isAttached()) return;
 
     getHolder().removeCallback(mSurfaceCallback);
+    releaseAccessibilityNodeProvider();
 
     mNativeView.destroy();
     mNativeView = null;
@@ -753,9 +754,7 @@ protected void onAttachedToWindow() {
   @Override
   protected void onDetachedFromWindow() {
     super.onDetachedFromWindow();
-
-    mAccessibilityNodeProvider.release();
-    mAccessibilityNodeProvider = null;
+    releaseAccessibilityNodeProvider();
   }
 
   // TODO(mattcarroll): Confer with Ian as to why we need this method. Delete if possible, otherwise
@@ -780,6 +779,13 @@ public AccessibilityNodeProvider getAccessibilityNodeProvider() {
     }
   }
 
+  private void releaseAccessibilityNodeProvider() {
+    if (mAccessibilityNodeProvider != null) {
+      mAccessibilityNodeProvider.release();
+      mAccessibilityNodeProvider = null;
+    }
+  }
+
   @Override
   @TargetApi(Build.VERSION_CODES.N)
   @RequiresApi(Build.VERSION_CODES.N)