https://bugs.chromium.org/p/chromium/issues/detail?id=971949

gpu-buffer.diff

diff --git a/third_party/blink/renderer/modules/webgpu/gpu_buffer.cc b/third_party/blink/renderer/modules/webgpu/gpu_buffer.cc
index 9658796f2508..37a106c741f6 100644
--- a/third_party/blink/renderer/modules/webgpu/gpu_buffer.cc
+++ b/third_party/blink/renderer/modules/webgpu/gpu_buffer.cc
@ -127,6 +131,25 @@ void GPUBuffer::OnMapAsyncCallback(ScriptPromiseResolver* resolver,
             WTF::ArrayBufferContents::SharingType::kNotShared);
 
         mapped_buffer_ = DOMArrayBuffer::Create(contents);
+
+        auto* script_state = resolver->GetScriptState();
+        if (script_state->ContextIsValid()) {
+          ScriptState::Scope scope(script_state);
+
+          v8::Isolate* isolate = script_state->GetIsolate();
+          v8::Local<v8::Object> global = script_state->GetContext()->Global();
+
+          v8::Local<v8::Value> gpu_buffer_value = ToV8(this, global, isolate);
+          v8::Local<v8::Object> gpu_buffer_wrapper =
+              gpu_buffer_value->ToObject(script_state->GetContext())
+                  .ToLocalChecked();
+
+          v8::Local<v8::Value> mapped_buffer_wrapper =
+              ToV8(mapped_buffer_, global, isolate);
+          V8PrivateProperty::GetGPUBufferArrayBuffer(isolate).Set(
+              gpu_buffer_wrapper, mapped_buffer_wrapper);
+        }
+
         resolver->Resolve(mapped_buffer_);
       }
       break;
diff --git a/third_party/blink/renderer/platform/bindings/v8_private_property.h b/third_party/blink/renderer/platform/bindings/v8_private_property.h
index 9eb1a25df1a9..0b1eb6122d44 100644
--- a/third_party/blink/renderer/platform/bindings/v8_private_property.h
+++ b/third_party/blink/renderer/platform/bindings/v8_private_property.h
@@ -34,6 +34,7 @@ class ScriptWrappable;
   X(CustomElementLifecycle, DetachedCallback)         \
   X(DOMException, Error)                              \
   X(Global, Event)                                    \
+  X(GPUBuffer, ArrayBuffer)                           \
   X(IDBCursor, Request)                               \
   X(IntersectionObserver, Callback)                   \
   X(MessageChannel, Port1)                            \