replace nextNodeId/previousNodeId with hitTestPosition (#5066)

lib/ui/semantics.dart

@@ -488,8 +488,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     String increasedValue,
     String decreasedValue,
     TextDirection textDirection,
-    int nextNodeId,
-    int previousNodeId,
+    int hitTestPosition,
     Float64List transform,
     Int32List children,
   }) {
@@ -513,8 +512,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
                 increasedValue,
                 decreasedValue,
                 textDirection != null ? textDirection.index + 1 : 0,
-                nextNodeId ?? -1,
-                previousNodeId ?? -1,
+                hitTestPosition,
                 transform,
                 children,);
   }
@@ -537,8 +535,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     String increasedValue,
     String decreasedValue,
     int textDirection,
-    int nextNodeId,
-    int previousNodeId,
+    int hitTestPosition,
     Float64List transform,
     Int32List children,
   ) native 'SemanticsUpdateBuilder_updateNode';

lib/ui/semantics/semantics_node.h

@@ -82,8 +82,7 @@ struct SemanticsNode {
   std::string increasedValue;
   std::string decreasedValue;
   int32_t textDirection = 0;  // 0=unknown, 1=rtl, 2=ltr
-  int32_t nextNodeId = -1;
-  int32_t previousNodeId = -1;
+  int32_t hitTestPosition = -1;
 
   SkRect rect = SkRect::MakeEmpty();
   SkMatrix44 transform = SkMatrix44(SkMatrix44::kIdentity_Constructor);

lib/ui/semantics/semantics_update_builder.cc

@@ -52,8 +52,7 @@ void SemanticsUpdateBuilder::updateNode(int id,
                                         std::string increasedValue,
                                         std::string decreasedValue,
                                         int textDirection,
-                                        int nextNodeId,
-                                        int previousNodeId,
+                                        int hitTestPosition,
                                         const tonic::Float64List& transform,
                                         const tonic::Int32List& children) {
   SemanticsNode node;
@@ -72,8 +71,7 @@ void SemanticsUpdateBuilder::updateNode(int id,
   node.increasedValue = increasedValue;
   node.decreasedValue = decreasedValue;
   node.textDirection = textDirection;
-  node.nextNodeId = nextNodeId;
-  node.previousNodeId = previousNodeId;
+  node.hitTestPosition = hitTestPosition;
   node.transform.setColMajord(transform.data());
   node.children = std::vector<int32_t>(
       children.data(), children.data() + children.num_elements());

lib/ui/semantics/semantics_update_builder.h

@@ -43,8 +43,7 @@ class SemanticsUpdateBuilder
                   std::string increasedValue,
                   std::string decreasedValue,
                   int textDirection,
-                  int nextNodeId,
-                  int previousNodeId,
+                  int hitTestPosition,
                   const tonic::Float64List& transform,
                   const tonic::Int32List& children);
 

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

@@ -251,10 +251,6 @@ class AccessibilityBridge extends AccessibilityNodeProvider implements BasicMess
 
         result.setSelected(object.hasFlag(Flag.IS_SELECTED));
         result.setText(object.getValueLabelHint());
-        if (object.previousNodeId != -1
-            && Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
-            result.setTraversalAfter(mOwner, object.previousNodeId);
-        }
 
         // Accessibility Focus
         if (mA11yFocusedObject != null && mA11yFocusedObject.id == virtualViewId) {
@@ -744,7 +740,7 @@ class AccessibilityBridge extends AccessibilityNodeProvider implements BasicMess
         String decreasedValue;
         String hint;
         TextDirection textDirection;
-        int previousNodeId;
+        int hitTestPosition;
 
         boolean hadPreviousConfig = false;
         int previousFlags;
@@ -797,7 +793,7 @@ class AccessibilityBridge extends AccessibilityNodeProvider implements BasicMess
         void log(String indent, boolean recursive) {
           Log.i(TAG, indent + "SemanticsObject id=" + id + " label=" + label + " actions=" +  actions + " flags=" + flags + "\n" +
                      indent + "  +-- textDirection=" + textDirection  + "\n"+
-                     indent + "  +-- previousNodeId=" + previousNodeId  + "\n"+
+                     indent + "  +-- hitTestPosition=" + hitTestPosition  + "\n"+
                      indent + "  +-- rect.ltrb=(" + left + ", " + top + ", " + right + ", " + bottom + ")\n" +
                      indent + "  +-- transform=" + Arrays.toString(transform) + "\n");
           if (children != null && recursive) {
@@ -844,7 +840,7 @@ class AccessibilityBridge extends AccessibilityNodeProvider implements BasicMess
 
             textDirection = TextDirection.fromInt(buffer.getInt());
 
-            previousNodeId = buffer.getInt();
+            hitTestPosition = buffer.getInt();
 
             left = buffer.getFloat();
             top = buffer.getFloat();

shell/platform/android/platform_view_android.cc

@@ -243,7 +243,7 @@ void PlatformViewAndroid::UpdateSemantics(blink::SemanticsNodeUpdates update) {
         strings.push_back(node.hint);
       }
       buffer_int32[position++] = node.textDirection;
-      buffer_int32[position++] = node.previousNodeId;
+      buffer_int32[position++] = node.hitTestPosition;
       buffer_float32[position++] = node.rect.left();
       buffer_float32[position++] = node.rect.top();
       buffer_float32[position++] = node.rect.right();