diff --git a/DEPS b/DEPS
index 2ec7cd49..42d81d66 100644
--- a/DEPS
+++ b/DEPS
@@ -7,7 +7,7 @@ deps = {
   'src/third_party/libcxx': 'https://llvm.googlesource.com/llvm-project/libcxx@bd557f6f764d1e40b62528a13b124ce740624f8f',
   'src/third_party/libcxxabi': 'https://llvm.googlesource.com/llvm-project/libcxxabi@a4dda1589d37a7e4b4f7a81ebad01b1083f2e726',
   'src/third_party/googletest': 'https://github.com/google/googletest@7f036c5563af7d0329f20e8bb42effb04629f0c0',
-  'src/third_party/dart': 'https://dart.googlesource.com/sdk.git@2da4111d8d0cbf2a83c0662251508f017000da8a',
+  'src/third_party/dart': 'https://dart.googlesource.com/sdk.git@e927f58e327ae13d056a16bb2ebf618e071c20a7',
   'src/third_party/clang': {
     'packages': [
       {
diff --git a/flutter/shell/platform/common/accessibility_bridge.cc b/flutter/shell/platform/common/accessibility_bridge.cc
index 70934026..ca318e1f 100644
--- a/flutter/shell/platform/common/accessibility_bridge.cc
+++ b/flutter/shell/platform/common/accessibility_bridge.cc
@@ -524,6 +524,13 @@ void AccessibilityBridge::SetStringListAttributesFromFlutterUpdate(
   }
 }
 
+void AccessibilityBridge::SetIdentifierFromFlutterUpdate(
+    ui::AXNodeData& node_data,
+    const SemanticsNode& node) {
+  node_data.AddStringAttribute(ax::mojom::StringAttribute::kIdentifier,
+                               node.identifier);
+}
+
 void AccessibilityBridge::SetNameFromFlutterUpdate(ui::AXNodeData& node_data,
                                                    const SemanticsNode& node) {
   node_data.SetName(node.label);
@@ -635,6 +642,9 @@ AccessibilityBridge::FromFlutterSemanticsNode(
         flutter_node.custom_accessibility_actions +
             flutter_node.custom_accessibility_actions_count);
   }
+  if (flutter_node.identifier) {
+    result.identifier = std::string(flutter_node.identifier);
+  }
   return result;
 }
 
diff --git a/flutter/shell/platform/common/accessibility_bridge.h b/flutter/shell/platform/common/accessibility_bridge.h
index 9028aa32..334eb26a 100644
--- a/flutter/shell/platform/common/accessibility_bridge.h
+++ b/flutter/shell/platform/common/accessibility_bridge.h
@@ -182,6 +182,7 @@ class AccessibilityBridge
     std::vector<int32_t> children_in_traversal_order;
     std::vector<int32_t> custom_accessibility_actions;
     int32_t heading_level;
+    std::string identifier;
   } SemanticsNode;
 
   // See FlutterSemanticsCustomAction in embedder.h
@@ -226,6 +227,8 @@ class AccessibilityBridge
                                              const SemanticsNode& node);
   void SetStringListAttributesFromFlutterUpdate(ui::AXNodeData& node_data,
                                                 const SemanticsNode& node);
+  void SetIdentifierFromFlutterUpdate(ui::AXNodeData& node_data,
+                                      const SemanticsNode& node);
   void SetNameFromFlutterUpdate(ui::AXNodeData& node_data,
                                 const SemanticsNode& node);
   void SetValueFromFlutterUpdate(ui::AXNodeData& node_data,
diff --git a/flutter/shell/platform/common/client_wrapper/include/flutter/encodable_value.h b/flutter/shell/platform/common/client_wrapper/include/flutter/encodable_value.h
index e6eacad6..905ad222 100644
--- a/flutter/shell/platform/common/client_wrapper/include/flutter/encodable_value.h
+++ b/flutter/shell/platform/common/client_wrapper/include/flutter/encodable_value.h
@@ -9,6 +9,7 @@
 #include <cassert>
 #include <cstdint>
 #include <map>
+#include <optional>
 #include <string>
 #include <utility>
 #include <variant>
@@ -216,6 +217,23 @@ class EncodableValue : public internal::EncodableValueVariant {
     return std::get<int64_t>(*this);
   }
 
+  // Convenience method to simplify handling objects received from Flutter
+  // where the values may be larger than 32-bit, since they have the same type
+  // on the Dart side, but will be either 32-bit or 64-bit here depending on
+  // the value.
+  //
+  // Calling this method if the value doesn't contain either an int32_t or an
+  // int64_t will return std::nullopt.
+  std::optional<int64_t> TryGetLongValue() const {
+    if (std::holds_alternative<int32_t>(*this)) {
+      return std::get<int32_t>(*this);
+    }
+    if (std::holds_alternative<int64_t>(*this)) {
+      return std::get<int64_t>(*this);
+    }
+    return std::nullopt;
+  }
+
 // The C++ Standard Library implementations can get into issues with recursive
 // constraint satisfaction when (among other things) objects of this type (which
 // is an `std::variant` subclass) are put into containers like `std::vector`.
diff --git a/flutter/shell/platform/common/windowing.h b/flutter/shell/platform/common/windowing.h
index 5c37df32..beb2ca45 100644
--- a/flutter/shell/platform/common/windowing.h
+++ b/flutter/shell/platform/common/windowing.h
@@ -8,11 +8,12 @@
 namespace flutter {
 
 // Types of windows.
-// The value must match value from WindowType in the Dart code
-// in packages/flutter/lib/src/widgets/window.dart
 enum class WindowArchetype {
   // Regular top-level window.
   kRegular,
+
+  // Dialog window.
+  kDialog,
 };
 
 }  // namespace flutter
diff --git a/flutter/shell/platform/embedder/embedder.h b/flutter/shell/platform/embedder/embedder.h
index 9249f082..1fd58e5b 100644
--- a/flutter/shell/platform/embedder/embedder.h
+++ b/flutter/shell/platform/embedder/embedder.h
@@ -352,6 +352,8 @@ typedef struct {
   bool is_slider;
   /// Whether the semantics node represents a keyboard key.
   bool is_keyboard_key;
+  /// Whether to block a11y focus for the semantics node.
+  bool is_accessibility_focus_blocked;
 } FlutterSemanticsFlags;
 
 typedef enum {
@@ -1742,6 +1744,11 @@ typedef struct {
   /// heading; higher values (1, 2, …) indicate the heading rank, with lower
   /// numbers being higher-level headings.
   int32_t heading_level;
+  /// An identifier for the semantics node in native accessibility hierarchy.
+  /// This value should not be exposed to the users of the app.
+  /// This is usually used for UI testing with tools that work by querying the
+  /// native accessibility, like UI Automator, XCUITest, or Appium.
+  const char* identifier;
 } FlutterSemanticsNode2;
 
 /// `FlutterSemanticsCustomAction` ID used as a sentinel to signal the end of a
diff --git a/flutter/third_party/accessibility/ax/ax_active_popup.h b/flutter/third_party/accessibility/ax/ax_active_popup.h
index 94f15c66..39b8beda 100644
--- a/flutter/third_party/accessibility/ax/ax_active_popup.h
+++ b/flutter/third_party/accessibility/ax/ax_active_popup.h
@@ -5,7 +5,6 @@
 #ifndef UI_ACCESSIBILITY_AX_ACTIVE_POPUP_H_
 #define UI_ACCESSIBILITY_AX_ACTIVE_POPUP_H_
 
-#include <cstdint>
 #include <optional>
 
 #include "ax/ax_export.h"
diff --git a/flutter/third_party/accessibility/ax/ax_constants.h b/flutter/third_party/accessibility/ax/ax_constants.h
index e9e7388b..db93292e 100644
--- a/flutter/third_party/accessibility/ax/ax_constants.h
+++ b/flutter/third_party/accessibility/ax/ax_constants.h
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#ifndef UI_ACCESSIBILITY_AX_CONSTANTS_H_
+#define UI_ACCESSIBILITY_AX_CONSTANTS_H_
+
 #include <cstdint>
 
 namespace ax {
@@ -19,3 +22,5 @@ const int32_t kUnknownAriaColumnOrRowCount = -1;
 }  // namespace mojom
 
 }  // namespace ax
+
+#endif  // UI_ACCESSIBILITY_AX_CONSTANTS_H_
diff --git a/flutter/third_party/accessibility/ax/ax_enum_util.cc b/flutter/third_party/accessibility/ax/ax_enum_util.cc
index 120e0615..34d34c5a 100644
--- a/flutter/third_party/accessibility/ax/ax_enum_util.cc
+++ b/flutter/third_party/accessibility/ax/ax_enum_util.cc
@@ -1433,6 +1433,8 @@ const char* ToString(ax::mojom::StringAttribute string_attribute) {
       return "fontFamily";
     case ax::mojom::StringAttribute::kHtmlTag:
       return "htmlTag";
+    case ax::mojom::StringAttribute::kIdentifier:
+      return "identifier";
     case ax::mojom::StringAttribute::kImageAnnotation:
       return "imageAnnotation";
     case ax::mojom::StringAttribute::kImageDataUrl:
@@ -1493,6 +1495,8 @@ ax::mojom::StringAttribute ParseStringAttribute(const char* string_attribute) {
     return ax::mojom::StringAttribute::kFontFamily;
   if (0 == strcmp(string_attribute, "htmlTag"))
     return ax::mojom::StringAttribute::kHtmlTag;
+  if (0 == strcmp(string_attribute, "identifier"))
+    return ax::mojom::StringAttribute::kIdentifier;
   if (0 == strcmp(string_attribute, "imageAnnotation"))
     return ax::mojom::StringAttribute::kImageAnnotation;
   if (0 == strcmp(string_attribute, "imageDataUrl"))
diff --git a/flutter/third_party/accessibility/ax/ax_enums.h b/flutter/third_party/accessibility/ax/ax_enums.h
index 1a444cde..70f2e379 100644
--- a/flutter/third_party/accessibility/ax/ax_enums.h
+++ b/flutter/third_party/accessibility/ax/ax_enums.h
@@ -533,6 +533,7 @@ enum class StringAttribute {
   // Only present when different from parent.
   kFontFamily,
   kHtmlTag,
+  kIdentifier,
   // Stores an automatic image annotation if one is available. Only valid on
   // ax::mojom::Role::kImage. See kImageAnnotationStatus, too.
   kImageAnnotation,
diff --git a/flutter/third_party/accessibility/ax/ax_event_generator.h b/flutter/third_party/accessibility/ax/ax_event_generator.h
index 63d43525..688cffcd 100644
--- a/flutter/third_party/accessibility/ax/ax_event_generator.h
+++ b/flutter/third_party/accessibility/ax/ax_event_generator.h
@@ -125,14 +125,9 @@ class AX_EXPORT AXEventGenerator : public AXTreeObserver {
     const EventParams& event_params;
   };
 
-  class AX_EXPORT Iterator {
+  class AX_EXPORT Iterator
+      : public std::iterator<std::input_iterator_tag, TargetedEvent> {
    public:
-    using iterator_category = std::input_iterator_tag;
-    using value_type = TargetedEvent;
-    using difference_type = std::ptrdiff_t;
-    using pointer = TargetedEvent*;
-    using reference = TargetedEvent&;
-
     Iterator(
         const std::map<AXNode*, std::set<EventParams>>& map,
         const std::map<AXNode*, std::set<EventParams>>::const_iterator& head);
diff --git a/flutter/third_party/accessibility/ax/ax_event_intent.cc b/flutter/third_party/accessibility/ax/ax_event_intent.cc
index 6c571482..56b447a1 100644
--- a/flutter/third_party/accessibility/ax/ax_event_intent.cc
+++ b/flutter/third_party/accessibility/ax/ax_event_intent.cc
@@ -28,10 +28,6 @@ bool operator==(const AXEventIntent& a, const AXEventIntent& b) {
          a.move_direction == b.move_direction;
 }
 
-bool operator!=(const AXEventIntent& a, const AXEventIntent& b) {
-  return !(a == b);
-}
-
 std::string AXEventIntent::ToString() const {
   return std::string("AXEventIntent(") + ui::ToString(command) + ',' +
          ui::ToString(text_boundary) + ',' + ui::ToString(move_direction) + ')';
diff --git a/flutter/third_party/accessibility/ax/ax_event_intent.h b/flutter/third_party/accessibility/ax/ax_event_intent.h
index 6ecfec10..73916cd7 100644
--- a/flutter/third_party/accessibility/ax/ax_event_intent.h
+++ b/flutter/third_party/accessibility/ax/ax_event_intent.h
@@ -27,8 +27,6 @@ struct AX_BASE_EXPORT AXEventIntent final {
 
   friend AX_BASE_EXPORT bool operator==(const AXEventIntent& a,
                                         const AXEventIntent& b);
-  friend AX_BASE_EXPORT bool operator!=(const AXEventIntent& a,
-                                        const AXEventIntent& b);
 
   ax::mojom::Command command = ax::mojom::Command::kType;
   // TODO(nektar): Split TextBoundary into TextUnit and TextBoundary.
diff --git a/flutter/third_party/accessibility/ax/ax_node_data.cc b/flutter/third_party/accessibility/ax/ax_node_data.cc
index f13be3d2..48cbc7ce 100644
--- a/flutter/third_party/accessibility/ax/ax_node_data.cc
+++ b/flutter/third_party/accessibility/ax/ax_node_data.cc
@@ -1465,6 +1465,9 @@ std::string AXNodeData::ToString() const {
       case ax::mojom::StringAttribute::kHtmlTag:
         result += " html_tag=" + value;
         break;
+      case ax::mojom::StringAttribute::kIdentifier:
+        result += " identifer=" + value;
+        break;
       case ax::mojom::StringAttribute::kImageAnnotation:
         result += " image_annotation=" + value;
         break;
diff --git a/flutter/third_party/accessibility/ax/platform/ax_platform_node_delegate_base.cc b/flutter/third_party/accessibility/ax/platform/ax_platform_node_delegate_base.cc
index 501c7509..52288f6f 100644
--- a/flutter/third_party/accessibility/ax/platform/ax_platform_node_delegate_base.cc
+++ b/flutter/third_party/accessibility/ax/platform/ax_platform_node_delegate_base.cc
@@ -12,6 +12,7 @@
 #include "ax/ax_role_properties.h"
 #include "ax/ax_tree_data.h"
 #include "base/no_destructor.h"
+#include "base/string_utils.h"
 
 #include "ax_platform_node.h"
 #include "ax_platform_node_base.h"
@@ -629,7 +630,7 @@ std::set<AXPlatformNode*> AXPlatformNodeDelegateBase::GetReverseRelations(
 }
 
 std::u16string AXPlatformNodeDelegateBase::GetAuthorUniqueId() const {
-  return std::u16string();
+  return base::UTF8ToUTF16(GetData().GetStringAttribute(ax::mojom::StringAttribute::kIdentifier));
 }
 
 const AXUniqueId& AXPlatformNodeDelegateBase::GetUniqueId() const {
diff --git a/flutter/third_party/accessibility/ax/platform/ax_platform_node_mac.h b/flutter/third_party/accessibility/ax/platform/ax_platform_node_mac.h
index 1de7f4bc..6719056e 100644
--- a/flutter/third_party/accessibility/ax/platform/ax_platform_node_mac.h
+++ b/flutter/third_party/accessibility/ax/platform/ax_platform_node_mac.h
@@ -8,7 +8,6 @@
 #import <Cocoa/Cocoa.h>
 
 #include "base/macros.h"
-#include "base/platform/darwin/scoped_nsobject.h"
 
 #include "ax/ax_export.h"
 
@@ -39,7 +38,7 @@ class AXPlatformNodeMac : public AXPlatformNodeBase {
  private:
   ~AXPlatformNodeMac() override;
 
-  base::scoped_nsobject<AXPlatformNodeCocoa> native_node_;
+  AXPlatformNodeCocoa* native_node_;
 
   BASE_DISALLOW_COPY_AND_ASSIGN(AXPlatformNodeMac);
 };
diff --git a/flutter/third_party/accessibility/ax/platform/ax_platform_node_mac.mm b/flutter/third_party/accessibility/ax/platform/ax_platform_node_mac.mm
index 572b2ca7..e16b08ac 100644
--- a/flutter/third_party/accessibility/ax/platform/ax_platform_node_mac.mm
+++ b/flutter/third_party/accessibility/ax/platform/ax_platform_node_mac.mm
@@ -28,8 +28,8 @@
 using ActionList = std::vector<std::pair<ax::mojom::Action, NSString*>>;
 
 struct AnnouncementSpec {
-  base::scoped_nsobject<NSString> announcement;
-  base::scoped_nsobject<NSWindow> window;
+  NSString* announcement;
+  NSWindow* window;
   bool is_polite;
 };
 
@@ -434,8 +434,8 @@ - (NSString*)getName {
     return nullptr;
 
   auto announcement = std::make_unique<AnnouncementSpec>();
-  announcement->announcement = base::scoped_nsobject<NSString>([announcementText retain]);
-  announcement->window = base::scoped_nsobject<NSWindow>([[self AXWindowInternal] retain]);
+  announcement->announcement = announcementText;
+  announcement->window = [self AXWindowInternal];
   announcement->is_polite = liveStatus != "assertive";
   return announcement;
 }
@@ -498,7 +498,7 @@ - (NSArray*)accessibilityActionNames {
   if (!_node)
     return @[];
 
-  base::scoped_nsobject<NSMutableArray> axActions([[NSMutableArray alloc] init]);
+  NSMutableArray* axActions = [[NSMutableArray alloc] init];
 
   const ui::AXNodeData& data = _node->GetData();
   const ActionList& action_list = GetActionList();
@@ -514,7 +514,7 @@ - (NSArray*)accessibilityActionNames {
   if (AlsoUseShowMenuActionForDefaultAction(data))
     [axActions addObject:NSAccessibilityShowMenuAction];
 
-  return axActions.autorelease();
+  return axActions;
 }
 
 - (void)accessibilityPerformAction:(NSString*)action {
@@ -834,8 +834,7 @@ - (BOOL)isAccessibilitySelectorAllowed:(SEL)selector {
   // accessibility clients from trying to set the selection range, which won't
   // work because of 692362.
   if (selector == @selector(setAccessibilitySelectedText:) ||
-      selector == @selector(setAccessibilitySelectedTextRange:) ||
-      selector == @selector(setAccessibilitySelectedTextMarkerRange:)) {
+      selector == @selector(setAccessibilitySelectedTextRange:)) {
     return restriction != ax::mojom::Restriction::kReadOnly;
   }
 
@@ -973,9 +972,7 @@ - (NSAttributedString*)accessibilityAttributedStringForRange:(NSRange)range {
   if (!_node)
     return nil;
   // TODO(https://crbug.com/958811): Implement this for real.
-  base::scoped_nsobject<NSAttributedString> attributedString(
-      [[NSAttributedString alloc] initWithString:[self accessibilityStringForRange:range]]);
-  return attributedString.autorelease();
+  return [[NSAttributedString alloc] initWithString:[self accessibilityStringForRange:range]];
 }
 
 - (NSData*)accessibilityRTFForRange:(NSRange)range {
@@ -1085,8 +1082,8 @@ - (BOOL)isAccessibilityFocused {
 
 gfx::NativeViewAccessible AXPlatformNodeMac::GetNativeViewAccessible() {
   if (!native_node_)
-    native_node_.reset([[AXPlatformNodeCocoa alloc] initWithNode:this]);
-  return native_node_.get();
+    native_node_ = [[AXPlatformNodeCocoa alloc] initWithNode:this];
+  return native_node_;
 }
 
 void AXPlatformNodeMac::NotifyAccessibilityEvent(ax::mojom::Event event_type) {