Adds a platfromViewId to SemanticsNode

lib/ui/semantics.dart

@@ -601,6 +601,11 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
   /// The fields 'textSelectionBase' and 'textSelectionExtent' describe the
   /// currently selected text within `value`.
   ///
+  /// The field `platformViewId` references the platform view, whose semantics
+  /// nodes will be added as children to this node. If a platform view is
+  /// specified, `childrenInHitTestOrder` and `childrenInTraversalOrder` must be
+  /// empty.
+  ///
   /// For scrollable nodes `scrollPosition` describes the current scroll
   /// position in logical pixel. `scrollExtentMax` and `scrollExtentMin`
   /// describe the maximum and minimum in-rage values that `scrollPosition` can
@@ -629,6 +634,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     int actions,
     int textSelectionBase,
     int textSelectionExtent,
+    int platformViewId,
     int scrollChildren,
     int scrollIndex,
     double scrollPosition,
@@ -656,6 +662,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
       actions,
       textSelectionBase,
       textSelectionExtent,
+      platformViewId,
       scrollChildren,
       scrollIndex,
       scrollPosition,
@@ -685,6 +692,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     int actions,
     int textSelectionBase,
     int textSelectionExtent,
+    int platformViewId,
     int scrollChildren,
     int scrollIndex,
     double scrollPosition,

lib/ui/semantics/semantics_node.h

@@ -86,6 +86,7 @@ struct SemanticsNode {
   int32_t actions = 0;
   int32_t textSelectionBase = -1;
   int32_t textSelectionExtent = -1;
+  int32_t platformViewId = -1;
   int32_t scrollChildren = 0;
   int32_t scrollIndex = 0;
   double scrollPosition = std::nan("");

lib/ui/semantics/semantics_update_builder.cc

@@ -41,6 +41,7 @@ void SemanticsUpdateBuilder::updateNode(
     int actions,
     int textSelectionBase,
     int textSelectionExtent,
+    int platformViewId,
     int scrollChildren,
     int scrollIndex,
     double scrollPosition,
@@ -68,6 +69,7 @@ void SemanticsUpdateBuilder::updateNode(
   node.actions = actions;
   node.textSelectionBase = textSelectionBase;
   node.textSelectionExtent = textSelectionExtent;
+  node.platformViewId = platformViewId;
   node.scrollChildren = scrollChildren;
   node.scrollIndex = scrollIndex;
   node.scrollPosition = scrollPosition;

lib/ui/semantics/semantics_update_builder.h

@@ -29,6 +29,7 @@ class SemanticsUpdateBuilder
                   int actions,
                   int textSelectionBase,
                   int textSelectionExtent,
+                  int platformViewId,
                   int scrollChildren,
                   int scrollIndex,
                   double scrollPosition,

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

@@ -1614,6 +1614,7 @@ private static boolean nullableHasAncestor(SemanticsNode target, Predicate<Seman
         private int actions;
         private int textSelectionBase;
         private int textSelectionExtent;
+        private int platformViewId;
         private int scrollChildren;
         private int scrollIndex;
         private float scrollPosition;
@@ -1748,6 +1749,7 @@ private void updateWith(@NonNull ByteBuffer buffer, @NonNull String[] strings) {
             actions = buffer.getInt();
             textSelectionBase = buffer.getInt();
             textSelectionExtent = buffer.getInt();
+            platformViewId = buffer.getInt();
             scrollChildren = buffer.getInt();
             scrollIndex = buffer.getInt();
             scrollPosition = buffer.getFloat();

shell/platform/android/platform_view_android.cc

@@ -208,7 +208,7 @@ void PlatformViewAndroid::DispatchSemanticsAction(JNIEnv* env,
 void PlatformViewAndroid::UpdateSemantics(
     blink::SemanticsNodeUpdates update,
     blink::CustomAccessibilityActionUpdates actions) {
-  constexpr size_t kBytesPerNode = 38 * sizeof(int32_t);
+  constexpr size_t kBytesPerNode = 39 * sizeof(int32_t);
   constexpr size_t kBytesPerChild = sizeof(int32_t);
   constexpr size_t kBytesPerAction = 4 * sizeof(int32_t);
 
@@ -244,6 +244,7 @@ void PlatformViewAndroid::UpdateSemantics(
       buffer_int32[position++] = node.actions;
       buffer_int32[position++] = node.textSelectionBase;
       buffer_int32[position++] = node.textSelectionExtent;
+      buffer_int32[position++] = node.platformViewId;
       buffer_int32[position++] = node.scrollChildren;
       buffer_int32[position++] = node.scrollIndex;
       buffer_float32[position++] = (float)node.scrollPosition;