Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

8 files changed, 2917 insertions, 0 deletions

diff --git a/dom/webgpu/ipc/PWebGPU.ipdl b/dom/webgpu/ipc/PWebGPU.ipdl
new file mode 100644
index 0000000000..3bdc49fa4d
--- /dev/null
+++ b/dom/webgpu/ipc/PWebGPU.ipdl
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+using mozilla::layers::RGBDescriptor from "mozilla/layers/LayersSurfaces.h";
+using mozilla::layers::RemoteTextureId from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::RemoteTextureOwnerId from "mozilla/layers/LayersTypes.h";
+using mozilla::webgpu::RawId from "mozilla/webgpu/WebGPUTypes.h";
+using mozilla::dom::GPURequestAdapterOptions from "mozilla/dom/WebGPUBinding.h";
+using mozilla::dom::GPUCommandBufferDescriptor from "mozilla/dom/WebGPUBinding.h";
+using mozilla::dom::GPUBufferDescriptor from "mozilla/dom/WebGPUBinding.h";
+using mozilla::webgpu::MaybeScopedError from "mozilla/webgpu/WebGPUTypes.h";
+using mozilla::webgpu::WebGPUCompilationMessage from "mozilla/webgpu/WebGPUTypes.h";
+[MoveOnly] using class mozilla::ipc::UnsafeSharedMemoryHandle from "mozilla/ipc/RawShmem.h";
+
+include "mozilla/ipc/ByteBufUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+include "mozilla/webgpu/WebGPUSerialize.h";
+include "mozilla/layers/WebRenderMessageUtils.h";
+include protocol PCanvasManager;
+include PWebGPUTypes;
+
+namespace mozilla {
+namespace webgpu {
+
+/**
+ * Represents the connection between a WebGPUChild actor that issues WebGPU
+ * command from the content process, and a WebGPUParent in the compositor
+ * process that runs the commands.
+ */
+async protocol PWebGPU
+{
+  manager PCanvasManager;
+
+parent:
+  async DeviceAction(RawId selfId, ByteBuf buf);
+  async DeviceActionWithAck(RawId selfId, ByteBuf buf) returns (bool dummy);
+  async TextureAction(RawId selfId, RawId aDeviceId, ByteBuf buf);
+  async CommandEncoderAction(RawId selfId, RawId aDeviceId, ByteBuf buf);
+  async BumpImplicitBindGroupLayout(RawId pipelineId, bool isCompute, uint32_t index, RawId assignId);
+
+  async CreateBuffer(RawId deviceId, RawId bufferId, GPUBufferDescriptor desc, UnsafeSharedMemoryHandle shm);
+
+  async InstanceRequestAdapter(GPURequestAdapterOptions options, RawId[] ids) returns (ByteBuf byteBuf);
+  async AdapterRequestDevice(RawId selfId, ByteBuf buf, RawId newId) returns (bool success);
+  async AdapterDestroy(RawId selfId);
+  // TODO: We want to return an array of compilation messages.
+  async DeviceCreateShaderModule(RawId selfId, RawId bufferId, nsString label, nsCString code) returns (WebGPUCompilationMessage[] messages);
+  async BufferMap(RawId selfId, uint32_t aMode, uint64_t offset, uint64_t size) returns (BufferMapResult result);
+  async BufferUnmap(RawId deviceId, RawId bufferId, bool flush);
+  async BufferDestroy(RawId selfId);
+  async BufferDrop(RawId selfId);
+  async TextureDestroy(RawId selfId);
+  async TextureViewDestroy(RawId selfId);
+  async SamplerDestroy(RawId selfId);
+  async DeviceDestroy(RawId selfId);
+
+  async CommandEncoderFinish(RawId selfId, RawId deviceId, GPUCommandBufferDescriptor desc);
+  async CommandEncoderDestroy(RawId selfId);
+  async CommandBufferDestroy(RawId selfId);
+  async RenderBundleDestroy(RawId selfId);
+  async QueueSubmit(RawId selfId, RawId aDeviceId, RawId[] commandBuffers);
+  async QueueWriteAction(RawId selfId, RawId aDeviceId, ByteBuf buf, UnsafeSharedMemoryHandle shmem);
+
+  async BindGroupLayoutDestroy(RawId selfId);
+  async PipelineLayoutDestroy(RawId selfId);
+  async BindGroupDestroy(RawId selfId);
+  async ShaderModuleDestroy(RawId selfId);
+  async ComputePipelineDestroy(RawId selfId);
+  async RenderPipelineDestroy(RawId selfId);
+  async ImplicitLayoutDestroy(RawId implicitPlId, RawId[] implicitBglIds);
+  async DeviceCreateSwapChain(RawId selfId, RawId queueId, RGBDescriptor desc, RawId[] bufferIds, RemoteTextureOwnerId ownerId);
+  async SwapChainPresent(RawId textureId, RawId commandEncoderId, RemoteTextureId remoteTextureId, RemoteTextureOwnerId remoteTextureOwnerId);
+  async SwapChainDestroy(RemoteTextureOwnerId ownerId);
+
+  async DevicePushErrorScope(RawId selfId);
+  async DevicePopErrorScope(RawId selfId) returns (MaybeScopedError maybeError);
+
+  // Generate an error on the Device timeline for `deviceId`.
+  // The `message` parameter is interpreted as UTF-8.
+  async GenerateError(RawId deviceId, nsCString message);
+
+child:
+  async DeviceUncapturedError(RawId aDeviceId, nsCString message);
+  async DropAction(ByteBuf buf);
+  async __delete__();
+};
+
+} // webgpu
+} // mozilla
diff --git a/dom/webgpu/ipc/PWebGPUTypes.ipdlh b/dom/webgpu/ipc/PWebGPUTypes.ipdlh
new file mode 100644
index 0000000000..98f062856c
--- /dev/null
+++ b/dom/webgpu/ipc/PWebGPUTypes.ipdlh
@@ -0,0 +1,26 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+using struct mozilla::null_t from "mozilla/ipc/IPCCore.h";
+
+namespace mozilla {
+namespace webgpu {
+
+struct BufferMapSuccess {
+    uint64_t offset;
+    uint64_t size;
+    bool writable;
+};
+
+struct BufferMapError {
+    nsCString message;
+};
+
+union BufferMapResult {
+    BufferMapSuccess;
+    BufferMapError;
+};
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/dom/webgpu/ipc/WebGPUChild.cpp b/dom/webgpu/ipc/WebGPUChild.cpp
new file mode 100644
index 0000000000..77a9556a2d
--- /dev/null
+++ b/dom/webgpu/ipc/WebGPUChild.cpp
@@ -0,0 +1,1249 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "WebGPUChild.h"
+#include "js/RootingAPI.h"
+#include "js/String.h"
+#include "js/TypeDecls.h"
+#include "js/Value.h"
+#include "js/Warnings.h"  // JS::WarnUTF8
+#include "mozilla/Attributes.h"
+#include "mozilla/EnumTypeTraits.h"
+#include "mozilla/dom/Console.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/WebGPUBinding.h"
+#include "mozilla/dom/GPUUncapturedErrorEvent.h"
+#include "mozilla/webgpu/ValidationError.h"
+#include "mozilla/webgpu/WebGPUTypes.h"
+#include "mozilla/webgpu/ffi/wgpu.h"
+#include "Adapter.h"
+#include "DeviceLostInfo.h"
+#include "PipelineLayout.h"
+#include "Sampler.h"
+#include "CompilationInfo.h"
+#include "mozilla/ipc/RawShmem.h"
+#include "nsGlobalWindowInner.h"
+
+namespace mozilla::webgpu {
+
+NS_IMPL_CYCLE_COLLECTION(WebGPUChild)
+
+void WebGPUChild::JsWarning(nsIGlobalObject* aGlobal,
+                            const nsACString& aMessage) {
+  const auto& flatString = PromiseFlatCString(aMessage);
+  if (aGlobal) {
+    dom::AutoJSAPI api;
+    if (api.Init(aGlobal)) {
+      JS::WarnUTF8(api.cx(), "%s", flatString.get());
+    }
+  } else {
+    printf_stderr("Validation error without device target: %s\n",
+                  flatString.get());
+  }
+}
+
+static ffi::WGPUCompareFunction ConvertCompareFunction(
+    const dom::GPUCompareFunction& aCompare) {
+  // Value of 0 = Undefined is reserved on the C side for "null" semantics.
+  return ffi::WGPUCompareFunction(UnderlyingValue(aCompare) + 1);
+}
+
+static ffi::WGPUTextureFormat ConvertTextureFormat(
+    const dom::GPUTextureFormat& aFormat) {
+  ffi::WGPUTextureFormat result = {ffi::WGPUTextureFormat_Sentinel};
+  switch (aFormat) {
+    case dom::GPUTextureFormat::R8unorm:
+      result.tag = ffi::WGPUTextureFormat_R8Unorm;
+      break;
+    case dom::GPUTextureFormat::R8snorm:
+      result.tag = ffi::WGPUTextureFormat_R8Snorm;
+      break;
+    case dom::GPUTextureFormat::R8uint:
+      result.tag = ffi::WGPUTextureFormat_R8Uint;
+      break;
+    case dom::GPUTextureFormat::R8sint:
+      result.tag = ffi::WGPUTextureFormat_R8Sint;
+      break;
+    case dom::GPUTextureFormat::R16uint:
+      result.tag = ffi::WGPUTextureFormat_R16Uint;
+      break;
+    case dom::GPUTextureFormat::R16sint:
+      result.tag = ffi::WGPUTextureFormat_R16Sint;
+      break;
+    case dom::GPUTextureFormat::R16float:
+      result.tag = ffi::WGPUTextureFormat_R16Float;
+      break;
+    case dom::GPUTextureFormat::Rg8unorm:
+      result.tag = ffi::WGPUTextureFormat_Rg8Unorm;
+      break;
+    case dom::GPUTextureFormat::Rg8snorm:
+      result.tag = ffi::WGPUTextureFormat_Rg8Snorm;
+      break;
+    case dom::GPUTextureFormat::Rg8uint:
+      result.tag = ffi::WGPUTextureFormat_Rg8Uint;
+      break;
+    case dom::GPUTextureFormat::Rg8sint:
+      result.tag = ffi::WGPUTextureFormat_Rg8Sint;
+      break;
+    case dom::GPUTextureFormat::R32uint:
+      result.tag = ffi::WGPUTextureFormat_R32Uint;
+      break;
+    case dom::GPUTextureFormat::R32sint:
+      result.tag = ffi::WGPUTextureFormat_R32Sint;
+      break;
+    case dom::GPUTextureFormat::R32float:
+      result.tag = ffi::WGPUTextureFormat_R32Float;
+      break;
+    case dom::GPUTextureFormat::Rg16uint:
+      result.tag = ffi::WGPUTextureFormat_Rg16Uint;
+      break;
+    case dom::GPUTextureFormat::Rg16sint:
+      result.tag = ffi::WGPUTextureFormat_Rg16Sint;
+      break;
+    case dom::GPUTextureFormat::Rg16float:
+      result.tag = ffi::WGPUTextureFormat_Rg16Float;
+      break;
+    case dom::GPUTextureFormat::Rgba8unorm:
+      result.tag = ffi::WGPUTextureFormat_Rgba8Unorm;
+      break;
+    case dom::GPUTextureFormat::Rgba8unorm_srgb:
+      result.tag = ffi::WGPUTextureFormat_Rgba8UnormSrgb;
+      break;
+    case dom::GPUTextureFormat::Rgba8snorm:
+      result.tag = ffi::WGPUTextureFormat_Rgba8Snorm;
+      break;
+    case dom::GPUTextureFormat::Rgba8uint:
+      result.tag = ffi::WGPUTextureFormat_Rgba8Uint;
+      break;
+    case dom::GPUTextureFormat::Rgba8sint:
+      result.tag = ffi::WGPUTextureFormat_Rgba8Sint;
+      break;
+    case dom::GPUTextureFormat::Bgra8unorm:
+      result.tag = ffi::WGPUTextureFormat_Bgra8Unorm;
+      break;
+    case dom::GPUTextureFormat::Bgra8unorm_srgb:
+      result.tag = ffi::WGPUTextureFormat_Bgra8UnormSrgb;
+      break;
+    case dom::GPUTextureFormat::Rgb9e5ufloat:
+      result.tag = ffi::WGPUTextureFormat_Rgb9e5Ufloat;
+      break;
+    case dom::GPUTextureFormat::Rgb10a2unorm:
+      result.tag = ffi::WGPUTextureFormat_Rgb10a2Unorm;
+      break;
+    case dom::GPUTextureFormat::Rg11b10float:
+      result.tag = ffi::WGPUTextureFormat_Rg11b10Float;
+      break;
+    case dom::GPUTextureFormat::Rg32uint:
+      result.tag = ffi::WGPUTextureFormat_Rg32Uint;
+      break;
+    case dom::GPUTextureFormat::Rg32sint:
+      result.tag = ffi::WGPUTextureFormat_Rg32Sint;
+      break;
+    case dom::GPUTextureFormat::Rg32float:
+      result.tag = ffi::WGPUTextureFormat_Rg32Float;
+      break;
+    case dom::GPUTextureFormat::Rgba16uint:
+      result.tag = ffi::WGPUTextureFormat_Rgba16Uint;
+      break;
+    case dom::GPUTextureFormat::Rgba16sint:
+      result.tag = ffi::WGPUTextureFormat_Rgba16Sint;
+      break;
+    case dom::GPUTextureFormat::Rgba16float:
+      result.tag = ffi::WGPUTextureFormat_Rgba16Float;
+      break;
+    case dom::GPUTextureFormat::Rgba32uint:
+      result.tag = ffi::WGPUTextureFormat_Rgba32Uint;
+      break;
+    case dom::GPUTextureFormat::Rgba32sint:
+      result.tag = ffi::WGPUTextureFormat_Rgba32Sint;
+      break;
+    case dom::GPUTextureFormat::Rgba32float:
+      result.tag = ffi::WGPUTextureFormat_Rgba32Float;
+      break;
+    case dom::GPUTextureFormat::Depth32float:
+      result.tag = ffi::WGPUTextureFormat_Depth32Float;
+      break;
+    case dom::GPUTextureFormat::Bc1_rgba_unorm:
+      result.tag = ffi::WGPUTextureFormat_Bc1RgbaUnorm;
+      break;
+    case dom::GPUTextureFormat::Bc1_rgba_unorm_srgb:
+      result.tag = ffi::WGPUTextureFormat_Bc1RgbaUnormSrgb;
+      break;
+    case dom::GPUTextureFormat::Bc4_r_unorm:
+      result.tag = ffi::WGPUTextureFormat_Bc4RUnorm;
+      break;
+    case dom::GPUTextureFormat::Bc4_r_snorm:
+      result.tag = ffi::WGPUTextureFormat_Bc4RSnorm;
+      break;
+    case dom::GPUTextureFormat::Bc2_rgba_unorm:
+      result.tag = ffi::WGPUTextureFormat_Bc2RgbaUnorm;
+      break;
+    case dom::GPUTextureFormat::Bc2_rgba_unorm_srgb:
+      result.tag = ffi::WGPUTextureFormat_Bc2RgbaUnormSrgb;
+      break;
+    case dom::GPUTextureFormat::Bc3_rgba_unorm:
+      result.tag = ffi::WGPUTextureFormat_Bc3RgbaUnorm;
+      break;
+    case dom::GPUTextureFormat::Bc3_rgba_unorm_srgb:
+      result.tag = ffi::WGPUTextureFormat_Bc3RgbaUnormSrgb;
+      break;
+    case dom::GPUTextureFormat::Bc5_rg_unorm:
+      result.tag = ffi::WGPUTextureFormat_Bc5RgUnorm;
+      break;
+    case dom::GPUTextureFormat::Bc5_rg_snorm:
+      result.tag = ffi::WGPUTextureFormat_Bc5RgSnorm;
+      break;
+    case dom::GPUTextureFormat::Bc6h_rgb_ufloat:
+      result.tag = ffi::WGPUTextureFormat_Bc6hRgbUfloat;
+      break;
+    case dom::GPUTextureFormat::Bc6h_rgb_float:
+      result.tag = ffi::WGPUTextureFormat_Bc6hRgbFloat;
+      break;
+    case dom::GPUTextureFormat::Bc7_rgba_unorm:
+      result.tag = ffi::WGPUTextureFormat_Bc7RgbaUnorm;
+      break;
+    case dom::GPUTextureFormat::Bc7_rgba_unorm_srgb:
+      result.tag = ffi::WGPUTextureFormat_Bc7RgbaUnormSrgb;
+      break;
+    case dom::GPUTextureFormat::Depth24plus:
+      result.tag = ffi::WGPUTextureFormat_Depth24Plus;
+      break;
+    case dom::GPUTextureFormat::Depth24plus_stencil8:
+      result.tag = ffi::WGPUTextureFormat_Depth24PlusStencil8;
+      break;
+    case dom::GPUTextureFormat::Depth32float_stencil8:
+      result.tag = ffi::WGPUTextureFormat_Depth32FloatStencil8;
+      break;
+    case dom::GPUTextureFormat::EndGuard_:
+      MOZ_ASSERT_UNREACHABLE();
+  }
+
+  // Clang will check for us that the switch above is exhaustive,
+  // but not if we add a 'default' case. So, check this here.
+  MOZ_ASSERT(result.tag != ffi::WGPUTextureFormat_Sentinel,
+             "unexpected texture format enum");
+
+  return result;
+}
+
+void WebGPUChild::ConvertTextureFormatRef(const dom::GPUTextureFormat& aInput,
+                                          ffi::WGPUTextureFormat& aOutput) {
+  aOutput = ConvertTextureFormat(aInput);
+}
+
+static UniquePtr<ffi::WGPUClient> initialize() {
+  ffi::WGPUInfrastructure infra = ffi::wgpu_client_new();
+  return UniquePtr<ffi::WGPUClient>{infra.client};
+}
+
+WebGPUChild::WebGPUChild() : mClient(initialize()) {}
+
+WebGPUChild::~WebGPUChild() = default;
+
+RefPtr<AdapterPromise> WebGPUChild::InstanceRequestAdapter(
+    const dom::GPURequestAdapterOptions& aOptions) {
+  const int max_ids = 10;
+  RawId ids[max_ids] = {0};
+  unsigned long count =
+      ffi::wgpu_client_make_adapter_ids(mClient.get(), ids, max_ids);
+
+  nsTArray<RawId> sharedIds(count);
+  for (unsigned long i = 0; i != count; ++i) {
+    sharedIds.AppendElement(ids[i]);
+  }
+
+  return SendInstanceRequestAdapter(aOptions, sharedIds)
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [](ipc::ByteBuf&& aInfoBuf) {
+            // Ideally, we'd just send an empty ByteBuf, but the IPC code
+            // complains if the capacity is zero...
+            // So for the case where an adapter wasn't found, we just
+            // transfer a single 0u64 in this buffer.
+            return aInfoBuf.mLen > sizeof(uint64_t)
+                       ? AdapterPromise::CreateAndResolve(std::move(aInfoBuf),
+                                                          __func__)
+                       : AdapterPromise::CreateAndReject(Nothing(), __func__);
+          },
+          [](const ipc::ResponseRejectReason& aReason) {
+            return AdapterPromise::CreateAndReject(Some(aReason), __func__);
+          });
+}
+
+Maybe<DeviceRequest> WebGPUChild::AdapterRequestDevice(
+    RawId aSelfId, const dom::GPUDeviceDescriptor& aDesc,
+    ffi::WGPULimits* aLimits) {
+  ffi::WGPUDeviceDescriptor desc = {};
+  ffi::wgpu_client_fill_default_limits(&desc.limits);
+
+  // webgpu::StringHelper label(aDesc.mLabel);
+  // desc.label = label.Get();
+
+  const auto featureBits = Adapter::MakeFeatureBits(aDesc.mRequiredFeatures);
+  if (!featureBits) {
+    return Nothing();
+  }
+  desc.features = *featureBits;
+
+  if (aDesc.mRequiredLimits.WasPassed()) {
+    for (const auto& entry : aDesc.mRequiredLimits.Value().Entries()) {
+      const uint32_t valueU32 =
+          entry.mValue < std::numeric_limits<uint32_t>::max()
+              ? entry.mValue
+              : std::numeric_limits<uint32_t>::max();
+      if (entry.mKey == u"maxTextureDimension1D"_ns) {
+        desc.limits.max_texture_dimension_1d = valueU32;
+      } else if (entry.mKey == u"maxTextureDimension2D"_ns) {
+        desc.limits.max_texture_dimension_2d = valueU32;
+      } else if (entry.mKey == u"maxTextureDimension3D"_ns) {
+        desc.limits.max_texture_dimension_3d = valueU32;
+      } else if (entry.mKey == u"maxTextureArrayLayers"_ns) {
+        desc.limits.max_texture_array_layers = valueU32;
+      } else if (entry.mKey == u"maxBindGroups"_ns) {
+        desc.limits.max_bind_groups = valueU32;
+      } else if (entry.mKey ==
+                 u"maxDynamicUniformBuffersPerPipelineLayout"_ns) {
+        desc.limits.max_dynamic_uniform_buffers_per_pipeline_layout = valueU32;
+      } else if (entry.mKey ==
+                 u"maxDynamicStorageBuffersPerPipelineLayout"_ns) {
+        desc.limits.max_dynamic_storage_buffers_per_pipeline_layout = valueU32;
+      } else if (entry.mKey == u"maxSampledTexturesPerShaderStage"_ns) {
+        desc.limits.max_sampled_textures_per_shader_stage = valueU32;
+      } else if (entry.mKey == u"maxSamplersPerShaderStage"_ns) {
+        desc.limits.max_samplers_per_shader_stage = valueU32;
+      } else if (entry.mKey == u"maxStorageBuffersPerShaderStage"_ns) {
+        desc.limits.max_storage_buffers_per_shader_stage = valueU32;
+      } else if (entry.mKey == u"maxStorageTexturesPerShaderStage"_ns) {
+        desc.limits.max_storage_textures_per_shader_stage = valueU32;
+      } else if (entry.mKey == u"maxUniformBuffersPerShaderStage"_ns) {
+        desc.limits.max_uniform_buffers_per_shader_stage = valueU32;
+      } else if (entry.mKey == u"maxUniformBufferBindingSize"_ns) {
+        desc.limits.max_uniform_buffer_binding_size = entry.mValue;
+      } else if (entry.mKey == u"maxStorageBufferBindingSize"_ns) {
+        desc.limits.max_storage_buffer_binding_size = entry.mValue;
+      } else if (entry.mKey == u"minUniformBufferOffsetAlignment"_ns) {
+        desc.limits.min_uniform_buffer_offset_alignment = valueU32;
+      } else if (entry.mKey == u"minStorageBufferOffsetAlignment"_ns) {
+        desc.limits.min_storage_buffer_offset_alignment = valueU32;
+      } else if (entry.mKey == u"maxVertexBuffers"_ns) {
+        desc.limits.max_vertex_buffers = valueU32;
+      } else if (entry.mKey == u"maxVertexAttributes"_ns) {
+        desc.limits.max_vertex_attributes = valueU32;
+      } else if (entry.mKey == u"maxVertexBufferArrayStride"_ns) {
+        desc.limits.max_vertex_buffer_array_stride = valueU32;
+      } else if (entry.mKey == u"maxComputeWorkgroupSizeX"_ns) {
+        desc.limits.max_compute_workgroup_size_x = valueU32;
+      } else if (entry.mKey == u"maxComputeWorkgroupSizeY"_ns) {
+        desc.limits.max_compute_workgroup_size_y = valueU32;
+      } else if (entry.mKey == u"maxComputeWorkgroupSizeZ"_ns) {
+        desc.limits.max_compute_workgroup_size_z = valueU32;
+      } else if (entry.mKey == u"maxComputeWorkgroupsPerDimension"_ns) {
+        desc.limits.max_compute_workgroups_per_dimension = valueU32;
+      } else {
+        NS_WARNING(nsPrintfCString("Requested limit '%s' is not recognized.",
+                                   NS_ConvertUTF16toUTF8(entry.mKey).get())
+                       .get());
+        return Nothing();
+      }
+
+      // TODO: maxInterStageShaderComponents
+      // TODO: maxComputeWorkgroupStorageSize
+      // TODO: maxComputeInvocationsPerWorkgroup
+    }
+  }
+
+  RawId id = ffi::wgpu_client_make_device_id(mClient.get(), aSelfId);
+
+  ByteBuf bb;
+  ffi::wgpu_client_serialize_device_descriptor(&desc, ToFFI(&bb));
+
+  DeviceRequest request;
+  request.mId = id;
+  request.mPromise = SendAdapterRequestDevice(aSelfId, std::move(bb), id);
+  *aLimits = desc.limits;
+
+  return Some(std::move(request));
+}
+
+RawId WebGPUChild::DeviceCreateBuffer(RawId aSelfId,
+                                      const dom::GPUBufferDescriptor& aDesc,
+                                      ipc::UnsafeSharedMemoryHandle&& aShmem) {
+  RawId bufferId = ffi::wgpu_client_make_buffer_id(mClient.get(), aSelfId);
+  if (!SendCreateBuffer(aSelfId, bufferId, aDesc, std::move(aShmem))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return bufferId;
+}
+
+RawId WebGPUChild::DeviceCreateTexture(RawId aSelfId,
+                                       const dom::GPUTextureDescriptor& aDesc) {
+  ffi::WGPUTextureDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+
+  // TODO: bug 1773723
+  desc.view_formats = {nullptr, 0};
+
+  if (aDesc.mSize.IsRangeEnforcedUnsignedLongSequence()) {
+    const auto& seq = aDesc.mSize.GetAsRangeEnforcedUnsignedLongSequence();
+    desc.size.width = seq.Length() > 0 ? seq[0] : 1;
+    desc.size.height = seq.Length() > 1 ? seq[1] : 1;
+    desc.size.depth_or_array_layers = seq.Length() > 2 ? seq[2] : 1;
+  } else if (aDesc.mSize.IsGPUExtent3DDict()) {
+    const auto& dict = aDesc.mSize.GetAsGPUExtent3DDict();
+    desc.size.width = dict.mWidth;
+    desc.size.height = dict.mHeight;
+    desc.size.depth_or_array_layers = dict.mDepthOrArrayLayers;
+  } else {
+    MOZ_CRASH("Unexpected union");
+  }
+  desc.mip_level_count = aDesc.mMipLevelCount;
+  desc.sample_count = aDesc.mSampleCount;
+  desc.dimension = ffi::WGPUTextureDimension(aDesc.mDimension);
+  desc.format = ConvertTextureFormat(aDesc.mFormat);
+  desc.usage = aDesc.mUsage;
+
+  ByteBuf bb;
+  RawId id = ffi::wgpu_client_create_texture(mClient.get(), aSelfId, &desc,
+                                             ToFFI(&bb));
+  if (!SendDeviceAction(aSelfId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+RawId WebGPUChild::TextureCreateView(
+    RawId aSelfId, RawId aDeviceId,
+    const dom::GPUTextureViewDescriptor& aDesc) {
+  ffi::WGPUTextureViewDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+
+  ffi::WGPUTextureFormat format = {ffi::WGPUTextureFormat_Sentinel};
+  if (aDesc.mFormat.WasPassed()) {
+    format = ConvertTextureFormat(aDesc.mFormat.Value());
+    desc.format = &format;
+  }
+  ffi::WGPUTextureViewDimension dimension =
+      ffi::WGPUTextureViewDimension_Sentinel;
+  if (aDesc.mDimension.WasPassed()) {
+    dimension = ffi::WGPUTextureViewDimension(aDesc.mDimension.Value());
+    desc.dimension = &dimension;
+  }
+
+  // Ideally we'd just do something like "aDesc.mMipLevelCount.ptrOr(nullptr)"
+  // but dom::Optional does not seem to have very many nice things.
+  uint32_t mipCount =
+      aDesc.mMipLevelCount.WasPassed() ? aDesc.mMipLevelCount.Value() : 0;
+  uint32_t layerCount =
+      aDesc.mArrayLayerCount.WasPassed() ? aDesc.mArrayLayerCount.Value() : 0;
+
+  desc.aspect = ffi::WGPUTextureAspect(aDesc.mAspect);
+  desc.base_mip_level = aDesc.mBaseMipLevel;
+  desc.mip_level_count = aDesc.mMipLevelCount.WasPassed() ? &mipCount : nullptr;
+  desc.base_array_layer = aDesc.mBaseArrayLayer;
+  desc.array_layer_count =
+      aDesc.mArrayLayerCount.WasPassed() ? &layerCount : nullptr;
+
+  ByteBuf bb;
+  RawId id = ffi::wgpu_client_create_texture_view(mClient.get(), aSelfId, &desc,
+                                                  ToFFI(&bb));
+  if (!SendTextureAction(aSelfId, aDeviceId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+RawId WebGPUChild::DeviceCreateSampler(RawId aSelfId,
+                                       const dom::GPUSamplerDescriptor& aDesc) {
+  ffi::WGPUSamplerDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+  desc.address_modes[0] = ffi::WGPUAddressMode(aDesc.mAddressModeU);
+  desc.address_modes[1] = ffi::WGPUAddressMode(aDesc.mAddressModeV);
+  desc.address_modes[2] = ffi::WGPUAddressMode(aDesc.mAddressModeW);
+  desc.mag_filter = ffi::WGPUFilterMode(aDesc.mMagFilter);
+  desc.min_filter = ffi::WGPUFilterMode(aDesc.mMinFilter);
+  desc.mipmap_filter = ffi::WGPUFilterMode(aDesc.mMipmapFilter);
+  desc.lod_min_clamp = aDesc.mLodMinClamp;
+  desc.lod_max_clamp = aDesc.mLodMaxClamp;
+
+  ffi::WGPUCompareFunction comparison = ffi::WGPUCompareFunction_Sentinel;
+  if (aDesc.mCompare.WasPassed()) {
+    comparison = ConvertCompareFunction(aDesc.mCompare.Value());
+    desc.compare = &comparison;
+  }
+
+  ByteBuf bb;
+  RawId id = ffi::wgpu_client_create_sampler(mClient.get(), aSelfId, &desc,
+                                             ToFFI(&bb));
+  if (!SendDeviceAction(aSelfId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+RawId WebGPUChild::DeviceCreateCommandEncoder(
+    RawId aSelfId, const dom::GPUCommandEncoderDescriptor& aDesc) {
+  ffi::WGPUCommandEncoderDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+
+  ByteBuf bb;
+  RawId id = ffi::wgpu_client_create_command_encoder(mClient.get(), aSelfId,
+                                                     &desc, ToFFI(&bb));
+  if (!SendDeviceAction(aSelfId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+RawId WebGPUChild::CommandEncoderFinish(
+    RawId aSelfId, RawId aDeviceId,
+    const dom::GPUCommandBufferDescriptor& aDesc) {
+  if (!SendCommandEncoderFinish(aSelfId, aDeviceId, aDesc)) {
+    MOZ_CRASH("IPC failure");
+  }
+  // We rely on knowledge that `CommandEncoderId` == `CommandBufferId`
+  // TODO: refactor this to truly behave as if the encoder is being finished,
+  // and a new command buffer ID is being created from it. Resolve the ID
+  // type aliasing at the place that introduces it: `wgpu-core`.
+  return aSelfId;
+}
+
+RawId WebGPUChild::RenderBundleEncoderFinish(
+    ffi::WGPURenderBundleEncoder& aEncoder, RawId aDeviceId,
+    const dom::GPURenderBundleDescriptor& aDesc) {
+  ffi::WGPURenderBundleDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+
+  ipc::ByteBuf bb;
+  RawId id = ffi::wgpu_client_create_render_bundle(
+      mClient.get(), &aEncoder, aDeviceId, &desc, ToFFI(&bb));
+
+  if (!SendDeviceAction(aDeviceId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+
+  return id;
+}
+
+RawId WebGPUChild::DeviceCreateBindGroupLayout(
+    RawId aSelfId, const dom::GPUBindGroupLayoutDescriptor& aDesc) {
+  struct OptionalData {
+    ffi::WGPUTextureViewDimension dim;
+    ffi::WGPURawTextureSampleType type;
+    ffi::WGPUTextureFormat format;
+  };
+  nsTArray<OptionalData> optional(aDesc.mEntries.Length());
+  for (const auto& entry : aDesc.mEntries) {
+    OptionalData data = {};
+    if (entry.mTexture.WasPassed()) {
+      const auto& texture = entry.mTexture.Value();
+      data.dim = ffi::WGPUTextureViewDimension(texture.mViewDimension);
+      switch (texture.mSampleType) {
+        case dom::GPUTextureSampleType::Float:
+          data.type = ffi::WGPURawTextureSampleType_Float;
+          break;
+        case dom::GPUTextureSampleType::Unfilterable_float:
+          data.type = ffi::WGPURawTextureSampleType_UnfilterableFloat;
+          break;
+        case dom::GPUTextureSampleType::Uint:
+          data.type = ffi::WGPURawTextureSampleType_Uint;
+          break;
+        case dom::GPUTextureSampleType::Sint:
+          data.type = ffi::WGPURawTextureSampleType_Sint;
+          break;
+        case dom::GPUTextureSampleType::Depth:
+          data.type = ffi::WGPURawTextureSampleType_Depth;
+          break;
+        case dom::GPUTextureSampleType::EndGuard_:
+          MOZ_ASSERT_UNREACHABLE();
+      }
+    }
+    if (entry.mStorageTexture.WasPassed()) {
+      const auto& texture = entry.mStorageTexture.Value();
+      data.dim = ffi::WGPUTextureViewDimension(texture.mViewDimension);
+      data.format = ConvertTextureFormat(texture.mFormat);
+    }
+    optional.AppendElement(data);
+  }
+
+  nsTArray<ffi::WGPUBindGroupLayoutEntry> entries(aDesc.mEntries.Length());
+  for (size_t i = 0; i < aDesc.mEntries.Length(); ++i) {
+    const auto& entry = aDesc.mEntries[i];
+    ffi::WGPUBindGroupLayoutEntry e = {};
+    e.binding = entry.mBinding;
+    e.visibility = entry.mVisibility;
+    if (entry.mBuffer.WasPassed()) {
+      switch (entry.mBuffer.Value().mType) {
+        case dom::GPUBufferBindingType::Uniform:
+          e.ty = ffi::WGPURawBindingType_UniformBuffer;
+          break;
+        case dom::GPUBufferBindingType::Storage:
+          e.ty = ffi::WGPURawBindingType_StorageBuffer;
+          break;
+        case dom::GPUBufferBindingType::Read_only_storage:
+          e.ty = ffi::WGPURawBindingType_ReadonlyStorageBuffer;
+          break;
+        case dom::GPUBufferBindingType::EndGuard_:
+          MOZ_ASSERT_UNREACHABLE();
+      }
+      e.has_dynamic_offset = entry.mBuffer.Value().mHasDynamicOffset;
+    }
+    if (entry.mTexture.WasPassed()) {
+      e.ty = ffi::WGPURawBindingType_SampledTexture;
+      e.view_dimension = &optional[i].dim;
+      e.texture_sample_type = &optional[i].type;
+      e.multisampled = entry.mTexture.Value().mMultisampled;
+    }
+    if (entry.mStorageTexture.WasPassed()) {
+      e.ty = entry.mStorageTexture.Value().mAccess ==
+                     dom::GPUStorageTextureAccess::Write_only
+                 ? ffi::WGPURawBindingType_WriteonlyStorageTexture
+                 : ffi::WGPURawBindingType_ReadonlyStorageTexture;
+      e.view_dimension = &optional[i].dim;
+      e.storage_texture_format = &optional[i].format;
+    }
+    if (entry.mSampler.WasPassed()) {
+      e.ty = ffi::WGPURawBindingType_Sampler;
+      switch (entry.mSampler.Value().mType) {
+        case dom::GPUSamplerBindingType::Filtering:
+          e.sampler_filter = true;
+          break;
+        case dom::GPUSamplerBindingType::Non_filtering:
+          break;
+        case dom::GPUSamplerBindingType::Comparison:
+          e.sampler_compare = true;
+          break;
+        case dom::GPUSamplerBindingType::EndGuard_:
+          MOZ_ASSERT_UNREACHABLE();
+      }
+    }
+    entries.AppendElement(e);
+  }
+
+  ffi::WGPUBindGroupLayoutDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+  desc.entries = entries.Elements();
+  desc.entries_length = entries.Length();
+
+  ByteBuf bb;
+  RawId id = ffi::wgpu_client_create_bind_group_layout(mClient.get(), aSelfId,
+                                                       &desc, ToFFI(&bb));
+  if (!SendDeviceAction(aSelfId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+RawId WebGPUChild::DeviceCreatePipelineLayout(
+    RawId aSelfId, const dom::GPUPipelineLayoutDescriptor& aDesc) {
+  nsTArray<ffi::WGPUBindGroupLayoutId> bindGroupLayouts(
+      aDesc.mBindGroupLayouts.Length());
+  for (const auto& layout : aDesc.mBindGroupLayouts) {
+    if (!layout->IsValid()) {
+      return 0;
+    }
+    bindGroupLayouts.AppendElement(layout->mId);
+  }
+
+  ffi::WGPUPipelineLayoutDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+  desc.bind_group_layouts = bindGroupLayouts.Elements();
+  desc.bind_group_layouts_length = bindGroupLayouts.Length();
+
+  ByteBuf bb;
+  RawId id = ffi::wgpu_client_create_pipeline_layout(mClient.get(), aSelfId,
+                                                     &desc, ToFFI(&bb));
+  if (!SendDeviceAction(aSelfId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+RawId WebGPUChild::DeviceCreateBindGroup(
+    RawId aSelfId, const dom::GPUBindGroupDescriptor& aDesc) {
+  if (!aDesc.mLayout->IsValid()) {
+    return 0;
+  }
+
+  nsTArray<ffi::WGPUBindGroupEntry> entries(aDesc.mEntries.Length());
+  for (const auto& entry : aDesc.mEntries) {
+    ffi::WGPUBindGroupEntry e = {};
+    e.binding = entry.mBinding;
+    if (entry.mResource.IsGPUBufferBinding()) {
+      const auto& bufBinding = entry.mResource.GetAsGPUBufferBinding();
+      e.buffer = bufBinding.mBuffer->mId;
+      e.offset = bufBinding.mOffset;
+      e.size = bufBinding.mSize.WasPassed() ? bufBinding.mSize.Value() : 0;
+    }
+    if (entry.mResource.IsGPUTextureView()) {
+      e.texture_view = entry.mResource.GetAsGPUTextureView()->mId;
+    }
+    if (entry.mResource.IsGPUSampler()) {
+      e.sampler = entry.mResource.GetAsGPUSampler()->mId;
+    }
+    entries.AppendElement(e);
+  }
+
+  ffi::WGPUBindGroupDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+  desc.layout = aDesc.mLayout->mId;
+  desc.entries = entries.Elements();
+  desc.entries_length = entries.Length();
+
+  ByteBuf bb;
+  RawId id = ffi::wgpu_client_create_bind_group(mClient.get(), aSelfId, &desc,
+                                                ToFFI(&bb));
+  if (!SendDeviceAction(aSelfId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+MOZ_CAN_RUN_SCRIPT void reportCompilationMessagesToConsole(
+    const RefPtr<ShaderModule>& aShaderModule,
+    const nsTArray<WebGPUCompilationMessage>& aMessages) {
+  auto* global = aShaderModule->GetParentObject();
+
+  dom::AutoJSAPI api;
+  if (!api.Init(global)) {
+    return;
+  }
+
+  const auto& cx = api.cx();
+
+  ErrorResult rv;
+  RefPtr<dom::Console> console =
+      nsGlobalWindowInner::Cast(global->AsInnerWindow())->GetConsole(cx, rv);
+  if (rv.Failed()) {
+    return;
+  }
+
+  dom::GlobalObject globalObj(cx, global->GetGlobalJSObject());
+
+  dom::Sequence<JS::Value> args;
+  dom::SequenceRooter<JS::Value> msgArgsRooter(cx, &args);
+  auto SetSingleStrAsArgs =
+      [&](const nsString& message, dom::Sequence<JS::Value>* args)
+          MOZ_CAN_RUN_SCRIPT {
+            args->Clear();
+            JS::Rooted<JSString*> jsStr(
+                cx, JS_NewUCStringCopyN(cx, message.Data(), message.Length()));
+            if (!jsStr) {
+              return;
+            }
+            JS::Rooted<JS::Value> val(cx, JS::StringValue(jsStr));
+            if (!args->AppendElement(val, fallible)) {
+              return;
+            }
+          };
+
+  nsString label;
+  aShaderModule->GetLabel(label);
+  auto appendNiceLabelIfPresent = [&label](nsString* buf) MOZ_CAN_RUN_SCRIPT {
+    if (!label.IsEmpty()) {
+      buf->AppendLiteral(u" \"");
+      buf->Append(label);
+      buf->AppendLiteral(u"\"");
+    }
+  };
+
+  // We haven't actually inspected a message for severity, but
+  // it doesn't actually matter, since we don't do anything at
+  // this level.
+  auto highestSeveritySeen = WebGPUCompilationMessageType::Info;
+  uint64_t errorCount = 0;
+  uint64_t warningCount = 0;
+  uint64_t infoCount = 0;
+  for (const auto& message : aMessages) {
+    bool higherThanSeen =
+        static_cast<std::underlying_type_t<WebGPUCompilationMessageType>>(
+            message.messageType) <
+        static_cast<std::underlying_type_t<WebGPUCompilationMessageType>>(
+            highestSeveritySeen);
+    if (higherThanSeen) {
+      highestSeveritySeen = message.messageType;
+    }
+    switch (message.messageType) {
+      case WebGPUCompilationMessageType::Error:
+        errorCount += 1;
+        break;
+      case WebGPUCompilationMessageType::Warning:
+        warningCount += 1;
+        break;
+      case WebGPUCompilationMessageType::Info:
+        infoCount += 1;
+        break;
+    }
+  }
+  switch (highestSeveritySeen) {
+    case WebGPUCompilationMessageType::Info:
+      // shouldn't happen, but :shrug:
+      break;
+    case WebGPUCompilationMessageType::Warning: {
+      nsString msg(
+          u"Encountered one or more warnings while creating shader module");
+      appendNiceLabelIfPresent(&msg);
+      SetSingleStrAsArgs(msg, &args);
+      console->Warn(globalObj, args);
+      break;
+    }
+    case WebGPUCompilationMessageType::Error: {
+      nsString msg(
+          u"Encountered one or more errors while creating shader module");
+      appendNiceLabelIfPresent(&msg);
+      SetSingleStrAsArgs(msg, &args);
+      console->Error(globalObj, args);
+      break;
+    }
+  }
+
+  nsString header;
+  header.AppendLiteral(u"WebGPU compilation info for shader module");
+  appendNiceLabelIfPresent(&header);
+  header.AppendLiteral(u" (");
+  header.AppendInt(errorCount);
+  header.AppendLiteral(u" error(s), ");
+  header.AppendInt(warningCount);
+  header.AppendLiteral(u" warning(s), ");
+  header.AppendInt(infoCount);
+  header.AppendLiteral(u" info)");
+  SetSingleStrAsArgs(header, &args);
+  console->GroupCollapsed(globalObj, args);
+
+  for (const auto& message : aMessages) {
+    SetSingleStrAsArgs(message.message, &args);
+    switch (message.messageType) {
+      case WebGPUCompilationMessageType::Error:
+        console->Error(globalObj, args);
+        break;
+      case WebGPUCompilationMessageType::Warning:
+        console->Warn(globalObj, args);
+        break;
+      case WebGPUCompilationMessageType::Info:
+        console->Info(globalObj, args);
+        break;
+    }
+  }
+  console->GroupEnd(globalObj);
+}
+
+MOZ_CAN_RUN_SCRIPT_FOR_DEFINITION already_AddRefed<ShaderModule>
+WebGPUChild::DeviceCreateShaderModule(
+    Device& aDevice, const dom::GPUShaderModuleDescriptor& aDesc,
+    RefPtr<dom::Promise> aPromise) {
+  RawId deviceId = aDevice.mId;
+  RawId moduleId =
+      ffi::wgpu_client_make_shader_module_id(mClient.get(), deviceId);
+
+  RefPtr<ShaderModule> shaderModule =
+      new ShaderModule(&aDevice, moduleId, aPromise);
+
+  nsString noLabel;
+  nsString& label = noLabel;
+  if (aDesc.mLabel.WasPassed()) {
+    label = aDesc.mLabel.Value();
+    shaderModule->SetLabel(label);
+  }
+  SendDeviceCreateShaderModule(deviceId, moduleId, label, aDesc.mCode)
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [aPromise,
+           shaderModule](nsTArray<WebGPUCompilationMessage>&& messages)
+              MOZ_CAN_RUN_SCRIPT {
+                if (!messages.IsEmpty()) {
+                  reportCompilationMessagesToConsole(shaderModule,
+                                                     std::cref(messages));
+                }
+                RefPtr<CompilationInfo> infoObject(
+                    new CompilationInfo(shaderModule));
+                infoObject->SetMessages(messages);
+                aPromise->MaybeResolve(infoObject);
+              },
+          [aPromise](const ipc::ResponseRejectReason& aReason) {
+            aPromise->MaybeRejectWithNotSupportedError("IPC error");
+          });
+
+  return shaderModule.forget();
+}
+
+RawId WebGPUChild::DeviceCreateComputePipelineImpl(
+    PipelineCreationContext* const aContext,
+    const dom::GPUComputePipelineDescriptor& aDesc, ByteBuf* const aByteBuf) {
+  ffi::WGPUComputePipelineDescriptor desc = {};
+  nsCString label, entryPoint;
+  if (aDesc.mLabel.WasPassed()) {
+    CopyUTF16toUTF8(aDesc.mLabel.Value(), label);
+    desc.label = label.get();
+  }
+  if (aDesc.mLayout.IsGPUAutoLayoutMode()) {
+    desc.layout = 0;
+  } else if (aDesc.mLayout.IsGPUPipelineLayout()) {
+    desc.layout = aDesc.mLayout.GetAsGPUPipelineLayout()->mId;
+  } else {
+    MOZ_ASSERT_UNREACHABLE();
+  }
+  desc.stage.module = aDesc.mCompute.mModule->mId;
+  CopyUTF16toUTF8(aDesc.mCompute.mEntryPoint, entryPoint);
+  desc.stage.entry_point = entryPoint.get();
+
+  RawId implicit_bgl_ids[WGPUMAX_BIND_GROUPS] = {};
+  RawId id = ffi::wgpu_client_create_compute_pipeline(
+      mClient.get(), aContext->mParentId, &desc, ToFFI(aByteBuf),
+      &aContext->mImplicitPipelineLayoutId, implicit_bgl_ids);
+
+  for (const auto& cur : implicit_bgl_ids) {
+    if (!cur) break;
+    aContext->mImplicitBindGroupLayoutIds.AppendElement(cur);
+  }
+
+  return id;
+}
+
+RawId WebGPUChild::DeviceCreateComputePipeline(
+    PipelineCreationContext* const aContext,
+    const dom::GPUComputePipelineDescriptor& aDesc) {
+  ByteBuf bb;
+  const RawId id = DeviceCreateComputePipelineImpl(aContext, aDesc, &bb);
+
+  if (!SendDeviceAction(aContext->mParentId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+RefPtr<PipelinePromise> WebGPUChild::DeviceCreateComputePipelineAsync(
+    PipelineCreationContext* const aContext,
+    const dom::GPUComputePipelineDescriptor& aDesc) {
+  ByteBuf bb;
+  const RawId id = DeviceCreateComputePipelineImpl(aContext, aDesc, &bb);
+
+  return SendDeviceActionWithAck(aContext->mParentId, std::move(bb))
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [id](bool aDummy) {
+            Unused << aDummy;
+            return PipelinePromise::CreateAndResolve(id, __func__);
+          },
+          [](const ipc::ResponseRejectReason& aReason) {
+            return PipelinePromise::CreateAndReject(aReason, __func__);
+          });
+}
+
+static ffi::WGPUMultisampleState ConvertMultisampleState(
+    const dom::GPUMultisampleState& aDesc) {
+  ffi::WGPUMultisampleState desc = {};
+  desc.count = aDesc.mCount;
+  desc.mask = aDesc.mMask;
+  desc.alpha_to_coverage_enabled = aDesc.mAlphaToCoverageEnabled;
+  return desc;
+}
+
+static ffi::WGPUBlendComponent ConvertBlendComponent(
+    const dom::GPUBlendComponent& aDesc) {
+  ffi::WGPUBlendComponent desc = {};
+  desc.src_factor = ffi::WGPUBlendFactor(aDesc.mSrcFactor);
+  desc.dst_factor = ffi::WGPUBlendFactor(aDesc.mDstFactor);
+  desc.operation = ffi::WGPUBlendOperation(aDesc.mOperation);
+  return desc;
+}
+
+static ffi::WGPUStencilFaceState ConvertStencilFaceState(
+    const dom::GPUStencilFaceState& aDesc) {
+  ffi::WGPUStencilFaceState desc = {};
+  desc.compare = ConvertCompareFunction(aDesc.mCompare);
+  desc.fail_op = ffi::WGPUStencilOperation(aDesc.mFailOp);
+  desc.depth_fail_op = ffi::WGPUStencilOperation(aDesc.mDepthFailOp);
+  desc.pass_op = ffi::WGPUStencilOperation(aDesc.mPassOp);
+  return desc;
+}
+
+static ffi::WGPUDepthStencilState ConvertDepthStencilState(
+    const dom::GPUDepthStencilState& aDesc) {
+  ffi::WGPUDepthStencilState desc = {};
+  desc.format = ConvertTextureFormat(aDesc.mFormat);
+  desc.depth_write_enabled = aDesc.mDepthWriteEnabled;
+  desc.depth_compare = ConvertCompareFunction(aDesc.mDepthCompare);
+  desc.stencil.front = ConvertStencilFaceState(aDesc.mStencilFront);
+  desc.stencil.back = ConvertStencilFaceState(aDesc.mStencilBack);
+  desc.stencil.read_mask = aDesc.mStencilReadMask;
+  desc.stencil.write_mask = aDesc.mStencilWriteMask;
+  desc.bias.constant = aDesc.mDepthBias;
+  desc.bias.slope_scale = aDesc.mDepthBiasSlopeScale;
+  desc.bias.clamp = aDesc.mDepthBiasClamp;
+  return desc;
+}
+
+RawId WebGPUChild::DeviceCreateRenderPipelineImpl(
+    PipelineCreationContext* const aContext,
+    const dom::GPURenderPipelineDescriptor& aDesc, ByteBuf* const aByteBuf) {
+  // A bunch of stack locals that we can have pointers into
+  nsTArray<ffi::WGPUVertexBufferLayout> vertexBuffers;
+  nsTArray<ffi::WGPUVertexAttribute> vertexAttributes;
+  ffi::WGPURenderPipelineDescriptor desc = {};
+  nsCString vsEntry, fsEntry;
+  ffi::WGPUIndexFormat stripIndexFormat = ffi::WGPUIndexFormat_Uint16;
+  ffi::WGPUFace cullFace = ffi::WGPUFace_Front;
+  ffi::WGPUVertexState vertexState = {};
+  ffi::WGPUFragmentState fragmentState = {};
+  nsTArray<ffi::WGPUColorTargetState> colorStates;
+  nsTArray<ffi::WGPUBlendState> blendStates;
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+
+  if (aDesc.mLayout.IsGPUAutoLayoutMode()) {
+    desc.layout = 0;
+  } else if (aDesc.mLayout.IsGPUPipelineLayout()) {
+    desc.layout = aDesc.mLayout.GetAsGPUPipelineLayout()->mId;
+  } else {
+    MOZ_ASSERT_UNREACHABLE();
+  }
+
+  {
+    const auto& stage = aDesc.mVertex;
+    vertexState.stage.module = stage.mModule->mId;
+    CopyUTF16toUTF8(stage.mEntryPoint, vsEntry);
+    vertexState.stage.entry_point = vsEntry.get();
+
+    for (const auto& vertex_desc : stage.mBuffers) {
+      ffi::WGPUVertexBufferLayout vb_desc = {};
+      if (!vertex_desc.IsNull()) {
+        const auto& vd = vertex_desc.Value();
+        vb_desc.array_stride = vd.mArrayStride;
+        vb_desc.step_mode = ffi::WGPUVertexStepMode(vd.mStepMode);
+        // Note: we are setting the length but not the pointer
+        vb_desc.attributes_length = vd.mAttributes.Length();
+        for (const auto& vat : vd.mAttributes) {
+          ffi::WGPUVertexAttribute ad = {};
+          ad.offset = vat.mOffset;
+          ad.format = ffi::WGPUVertexFormat(vat.mFormat);
+          ad.shader_location = vat.mShaderLocation;
+          vertexAttributes.AppendElement(ad);
+        }
+      }
+      vertexBuffers.AppendElement(vb_desc);
+    }
+    // Now patch up all the pointers to attribute lists.
+    size_t numAttributes = 0;
+    for (auto& vb_desc : vertexBuffers) {
+      vb_desc.attributes = vertexAttributes.Elements() + numAttributes;
+      numAttributes += vb_desc.attributes_length;
+    }
+
+    vertexState.buffers = vertexBuffers.Elements();
+    vertexState.buffers_length = vertexBuffers.Length();
+    desc.vertex = &vertexState;
+  }
+
+  if (aDesc.mFragment.WasPassed()) {
+    const auto& stage = aDesc.mFragment.Value();
+    fragmentState.stage.module = stage.mModule->mId;
+    CopyUTF16toUTF8(stage.mEntryPoint, fsEntry);
+    fragmentState.stage.entry_point = fsEntry.get();
+
+    // Note: we pre-collect the blend states into a different array
+    // so that we can have non-stale pointers into it.
+    for (const auto& colorState : stage.mTargets) {
+      ffi::WGPUColorTargetState desc = {};
+      desc.format = ConvertTextureFormat(colorState.mFormat);
+      desc.write_mask = colorState.mWriteMask;
+      colorStates.AppendElement(desc);
+      ffi::WGPUBlendState bs = {};
+      if (colorState.mBlend.WasPassed()) {
+        const auto& blend = colorState.mBlend.Value();
+        bs.alpha = ConvertBlendComponent(blend.mAlpha);
+        bs.color = ConvertBlendComponent(blend.mColor);
+      }
+      blendStates.AppendElement(bs);
+    }
+    for (size_t i = 0; i < colorStates.Length(); ++i) {
+      if (stage.mTargets[i].mBlend.WasPassed()) {
+        colorStates[i].blend = &blendStates[i];
+      }
+    }
+
+    fragmentState.targets = colorStates.Elements();
+    fragmentState.targets_length = colorStates.Length();
+    desc.fragment = &fragmentState;
+  }
+
+  {
+    const auto& prim = aDesc.mPrimitive;
+    desc.primitive.topology = ffi::WGPUPrimitiveTopology(prim.mTopology);
+    if (prim.mStripIndexFormat.WasPassed()) {
+      stripIndexFormat = ffi::WGPUIndexFormat(prim.mStripIndexFormat.Value());
+      desc.primitive.strip_index_format = &stripIndexFormat;
+    }
+    desc.primitive.front_face = ffi::WGPUFrontFace(prim.mFrontFace);
+    if (prim.mCullMode != dom::GPUCullMode::None) {
+      cullFace = prim.mCullMode == dom::GPUCullMode::Front ? ffi::WGPUFace_Front
+                                                           : ffi::WGPUFace_Back;
+      desc.primitive.cull_mode = &cullFace;
+    }
+  }
+  desc.multisample = ConvertMultisampleState(aDesc.mMultisample);
+
+  ffi::WGPUDepthStencilState depthStencilState = {};
+  if (aDesc.mDepthStencil.WasPassed()) {
+    depthStencilState = ConvertDepthStencilState(aDesc.mDepthStencil.Value());
+    desc.depth_stencil = &depthStencilState;
+  }
+
+  RawId implicit_bgl_ids[WGPUMAX_BIND_GROUPS] = {};
+  RawId id = ffi::wgpu_client_create_render_pipeline(
+      mClient.get(), aContext->mParentId, &desc, ToFFI(aByteBuf),
+      &aContext->mImplicitPipelineLayoutId, implicit_bgl_ids);
+
+  for (const auto& cur : implicit_bgl_ids) {
+    if (!cur) break;
+    aContext->mImplicitBindGroupLayoutIds.AppendElement(cur);
+  }
+
+  return id;
+}
+
+RawId WebGPUChild::DeviceCreateRenderPipeline(
+    PipelineCreationContext* const aContext,
+    const dom::GPURenderPipelineDescriptor& aDesc) {
+  ByteBuf bb;
+  const RawId id = DeviceCreateRenderPipelineImpl(aContext, aDesc, &bb);
+
+  if (!SendDeviceAction(aContext->mParentId, std::move(bb))) {
+    MOZ_CRASH("IPC failure");
+  }
+  return id;
+}
+
+RefPtr<PipelinePromise> WebGPUChild::DeviceCreateRenderPipelineAsync(
+    PipelineCreationContext* const aContext,
+    const dom::GPURenderPipelineDescriptor& aDesc) {
+  ByteBuf bb;
+  const RawId id = DeviceCreateRenderPipelineImpl(aContext, aDesc, &bb);
+
+  return SendDeviceActionWithAck(aContext->mParentId, std::move(bb))
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [id](bool aDummy) {
+            Unused << aDummy;
+            return PipelinePromise::CreateAndResolve(id, __func__);
+          },
+          [](const ipc::ResponseRejectReason& aReason) {
+            return PipelinePromise::CreateAndReject(aReason, __func__);
+          });
+}
+
+ipc::IPCResult WebGPUChild::RecvDeviceUncapturedError(
+    RawId aDeviceId, const nsACString& aMessage) {
+  auto targetIter = mDeviceMap.find(aDeviceId);
+  if (!aDeviceId || targetIter == mDeviceMap.end()) {
+    JsWarning(nullptr, aMessage);
+  } else {
+    auto* target = targetIter->second.get();
+    MOZ_ASSERT(target);
+    // We don't want to spam the errors to the console indefinitely
+    if (target->CheckNewWarning(aMessage)) {
+      JsWarning(target->GetOwnerGlobal(), aMessage);
+
+      dom::GPUUncapturedErrorEventInit init;
+      init.mError.SetAsGPUValidationError() =
+          new ValidationError(target->GetParentObject(), aMessage);
+      RefPtr<mozilla::dom::GPUUncapturedErrorEvent> event =
+          dom::GPUUncapturedErrorEvent::Constructor(
+              target, u"uncapturederror"_ns, init);
+      target->DispatchEvent(*event);
+    }
+  }
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUChild::RecvDropAction(const ipc::ByteBuf& aByteBuf) {
+  const auto* byteBuf = ToFFI(&aByteBuf);
+  ffi::wgpu_client_drop_action(mClient.get(), byteBuf);
+  return IPC_OK();
+}
+
+void WebGPUChild::DeviceCreateSwapChain(
+    RawId aSelfId, const RGBDescriptor& aRgbDesc, size_t maxBufferCount,
+    const layers::RemoteTextureOwnerId& aOwnerId) {
+  RawId queueId = aSelfId;  // TODO: multiple queues
+  nsTArray<RawId> bufferIds(maxBufferCount);
+  for (size_t i = 0; i < maxBufferCount; ++i) {
+    bufferIds.AppendElement(
+        ffi::wgpu_client_make_buffer_id(mClient.get(), aSelfId));
+  }
+  SendDeviceCreateSwapChain(aSelfId, queueId, aRgbDesc, bufferIds, aOwnerId);
+}
+
+void WebGPUChild::SwapChainPresent(RawId aTextureId,
+                                   const RemoteTextureId& aRemoteTextureId,
+                                   const RemoteTextureOwnerId& aOwnerId) {
+  // Hack: the function expects `DeviceId`, but it only uses it for `backend()`
+  // selection.
+  RawId encoderId = ffi::wgpu_client_make_encoder_id(mClient.get(), aTextureId);
+  SendSwapChainPresent(aTextureId, encoderId, aRemoteTextureId, aOwnerId);
+}
+
+void WebGPUChild::RegisterDevice(Device* const aDevice) {
+  mDeviceMap.insert({aDevice->mId, aDevice});
+}
+
+void WebGPUChild::UnregisterDevice(RawId aId) {
+  mDeviceMap.erase(aId);
+  if (IsOpen()) {
+    SendDeviceDestroy(aId);
+  }
+}
+
+void WebGPUChild::FreeUnregisteredInParentDevice(RawId aId) {
+  ffi::wgpu_client_kill_device_id(mClient.get(), aId);
+  mDeviceMap.erase(aId);
+}
+
+void WebGPUChild::ActorDestroy(ActorDestroyReason) {
+  // Resolving the promise could cause us to update the original map if the
+  // callee frees the Device objects immediately. Since any remaining entries
+  // in the map are no longer valid, we can just move the map onto the stack.
+  const auto deviceMap = std::move(mDeviceMap);
+  mDeviceMap.clear();
+
+  for (const auto& targetIter : deviceMap) {
+    RefPtr<Device> device = targetIter.second.get();
+    if (!device) {
+      // The Device may have gotten freed when we resolved the Promise for
+      // another Device in the map.
+      continue;
+    }
+
+    RefPtr<dom::Promise> promise = device->MaybeGetLost();
+    if (!promise) {
+      continue;
+    }
+
+    auto info = MakeRefPtr<DeviceLostInfo>(device->GetParentObject(),
+                                           u"WebGPUChild destroyed"_ns);
+
+    // We have strong references to both the Device and the DeviceLostInfo and
+    // the Promise objects on the stack which keeps them alive for long enough.
+    promise->MaybeResolve(info);
+  }
+}
+
+}  // namespace mozilla::webgpu
diff --git a/dom/webgpu/ipc/WebGPUChild.h b/dom/webgpu/ipc/WebGPUChild.h
new file mode 100644
index 0000000000..08f0c6ac77
--- /dev/null
+++ b/dom/webgpu/ipc/WebGPUChild.h
@@ -0,0 +1,146 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WEBGPU_CHILD_H_
+#define WEBGPU_CHILD_H_
+
+#include "mozilla/webgpu/PWebGPUChild.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/webgpu/ffi/wgpu.h"
+
+namespace mozilla {
+namespace ipc {
+class UnsafeSharedMemoryHandle;
+}  // namespace ipc
+namespace dom {
+struct GPURequestAdapterOptions;
+}  // namespace dom
+namespace layers {
+class CompositorBridgeChild;
+}  // namespace layers
+namespace webgpu {
+namespace ffi {
+struct WGPUClient;
+struct WGPULimits;
+struct WGPUTextureViewDescriptor;
+}  // namespace ffi
+
+using AdapterPromise =
+    MozPromise<ipc::ByteBuf, Maybe<ipc::ResponseRejectReason>, true>;
+using PipelinePromise = MozPromise<RawId, ipc::ResponseRejectReason, true>;
+using DevicePromise = MozPromise<bool, ipc::ResponseRejectReason, true>;
+
+struct PipelineCreationContext {
+  RawId mParentId = 0;
+  RawId mImplicitPipelineLayoutId = 0;
+  nsTArray<RawId> mImplicitBindGroupLayoutIds;
+};
+
+struct DeviceRequest {
+  RawId mId = 0;
+  RefPtr<DevicePromise> mPromise;
+  // Note: we could put `ffi::WGPULimits` in here as well,
+  //  but we don't want to #include ffi stuff in this header
+};
+
+ffi::WGPUByteBuf* ToFFI(ipc::ByteBuf* x);
+
+class WebGPUChild final : public PWebGPUChild, public SupportsWeakPtr {
+ public:
+  friend class layers::CompositorBridgeChild;
+
+  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(WebGPUChild)
+  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING_INHERITED(WebGPUChild)
+
+ public:
+  explicit WebGPUChild();
+
+  bool IsOpen() const { return CanSend(); }
+
+  RefPtr<AdapterPromise> InstanceRequestAdapter(
+      const dom::GPURequestAdapterOptions& aOptions);
+  Maybe<DeviceRequest> AdapterRequestDevice(
+      RawId aSelfId, const dom::GPUDeviceDescriptor& aDesc,
+      ffi::WGPULimits* aLimits);
+  RawId DeviceCreateBuffer(RawId aSelfId, const dom::GPUBufferDescriptor& aDesc,
+                           ipc::UnsafeSharedMemoryHandle&& aShmem);
+  RawId DeviceCreateTexture(RawId aSelfId,
+                            const dom::GPUTextureDescriptor& aDesc);
+  RawId TextureCreateView(RawId aSelfId, RawId aDeviceId,
+                          const dom::GPUTextureViewDescriptor& aDesc);
+  RawId DeviceCreateSampler(RawId aSelfId,
+                            const dom::GPUSamplerDescriptor& aDesc);
+  RawId DeviceCreateCommandEncoder(
+      RawId aSelfId, const dom::GPUCommandEncoderDescriptor& aDesc);
+  RawId CommandEncoderFinish(RawId aSelfId, RawId aDeviceId,
+                             const dom::GPUCommandBufferDescriptor& aDesc);
+  RawId RenderBundleEncoderFinish(ffi::WGPURenderBundleEncoder& aEncoder,
+                                  RawId aDeviceId,
+                                  const dom::GPURenderBundleDescriptor& aDesc);
+  RawId DeviceCreateBindGroupLayout(
+      RawId aSelfId, const dom::GPUBindGroupLayoutDescriptor& aDesc);
+  RawId DeviceCreatePipelineLayout(
+      RawId aSelfId, const dom::GPUPipelineLayoutDescriptor& aDesc);
+  RawId DeviceCreateBindGroup(RawId aSelfId,
+                              const dom::GPUBindGroupDescriptor& aDesc);
+  RawId DeviceCreateComputePipeline(
+      PipelineCreationContext* const aContext,
+      const dom::GPUComputePipelineDescriptor& aDesc);
+  RefPtr<PipelinePromise> DeviceCreateComputePipelineAsync(
+      PipelineCreationContext* const aContext,
+      const dom::GPUComputePipelineDescriptor& aDesc);
+  RawId DeviceCreateRenderPipeline(
+      PipelineCreationContext* const aContext,
+      const dom::GPURenderPipelineDescriptor& aDesc);
+  RefPtr<PipelinePromise> DeviceCreateRenderPipelineAsync(
+      PipelineCreationContext* const aContext,
+      const dom::GPURenderPipelineDescriptor& aDesc);
+  MOZ_CAN_RUN_SCRIPT already_AddRefed<ShaderModule> DeviceCreateShaderModule(
+      Device& aDevice, const dom::GPUShaderModuleDescriptor& aDesc,
+      RefPtr<dom::Promise> aPromise);
+
+  void DeviceCreateSwapChain(RawId aSelfId, const RGBDescriptor& aRgbDesc,
+                             size_t maxBufferCount,
+                             const layers::RemoteTextureOwnerId& aOwnerId);
+  void SwapChainPresent(RawId aTextureId,
+                        const RemoteTextureId& aRemoteTextureId,
+                        const RemoteTextureOwnerId& aOwnerId);
+
+  void RegisterDevice(Device* const aDevice);
+  void UnregisterDevice(RawId aId);
+  void FreeUnregisteredInParentDevice(RawId aId);
+
+  static void ConvertTextureFormatRef(const dom::GPUTextureFormat& aInput,
+                                      ffi::WGPUTextureFormat& aOutput);
+
+ private:
+  virtual ~WebGPUChild();
+
+  void JsWarning(nsIGlobalObject* aGlobal, const nsACString& aMessage);
+
+  RawId DeviceCreateComputePipelineImpl(
+      PipelineCreationContext* const aContext,
+      const dom::GPUComputePipelineDescriptor& aDesc,
+      ipc::ByteBuf* const aByteBuf);
+  RawId DeviceCreateRenderPipelineImpl(
+      PipelineCreationContext* const aContext,
+      const dom::GPURenderPipelineDescriptor& aDesc,
+      ipc::ByteBuf* const aByteBuf);
+
+  UniquePtr<ffi::WGPUClient> const mClient;
+  std::unordered_map<RawId, WeakPtr<Device>> mDeviceMap;
+
+ public:
+  ipc::IPCResult RecvDeviceUncapturedError(RawId aDeviceId,
+                                           const nsACString& aMessage);
+  ipc::IPCResult RecvDropAction(const ipc::ByteBuf& aByteBuf);
+  void ActorDestroy(ActorDestroyReason) override;
+};
+
+}  // namespace webgpu
+}  // namespace mozilla
+
+#endif  // WEBGPU_CHILD_H_
diff --git a/dom/webgpu/ipc/WebGPUParent.cpp b/dom/webgpu/ipc/WebGPUParent.cpp
new file mode 100644
index 0000000000..956d531e71
--- /dev/null
+++ b/dom/webgpu/ipc/WebGPUParent.cpp
@@ -0,0 +1,1128 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "WebGPUParent.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/webgpu/ffi/wgpu.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/ImageDataSerializer.h"
+#include "mozilla/layers/RemoteTextureMap.h"
+#include "mozilla/layers/TextureHost.h"
+#include "mozilla/layers/WebRenderImageHost.h"
+#include "mozilla/layers/WebRenderTextureHost.h"
+
+namespace mozilla::webgpu {
+
+const uint64_t POLL_TIME_MS = 100;
+
+static mozilla::LazyLogModule sLogger("WebGPU");
+
+// A fixed-capacity buffer for receiving textual error messages from
+// `wgpu_bindings`.
+//
+// The `ToFFI` method returns an `ffi::WGPUErrorBuffer` pointing to our
+// buffer, for you to pass to fallible FFI-visible `wgpu_bindings`
+// functions. These indicate failure by storing an error message in the
+// buffer, which you can retrieve by calling `GetError`.
+//
+// If you call `ToFFI` on this type, you must also call `GetError` to check for
+// an error. Otherwise, the destructor asserts.
+//
+// TODO: refactor this to avoid stack-allocating the buffer all the time.
+class ErrorBuffer {
+  // if the message doesn't fit, it will be truncated
+  static constexpr unsigned BUFFER_SIZE = 512;
+  char mUtf8[BUFFER_SIZE] = {};
+  bool mGuard = false;
+
+ public:
+  ErrorBuffer() { mUtf8[0] = 0; }
+  ErrorBuffer(const ErrorBuffer&) = delete;
+  ~ErrorBuffer() { MOZ_ASSERT(!mGuard); }
+
+  ffi::WGPUErrorBuffer ToFFI() {
+    mGuard = true;
+    ffi::WGPUErrorBuffer errorBuf = {mUtf8, BUFFER_SIZE};
+    return errorBuf;
+  }
+
+  // If an error message was stored in this buffer, return Some(m)
+  // where m is the message as a UTF-8 nsCString. Otherwise, return Nothing.
+  //
+  // Mark this ErrorBuffer as having been handled, so its destructor
+  // won't assert.
+  Maybe<nsCString> GetError() {
+    mGuard = false;
+    if (!mUtf8[0]) {
+      return Nothing();
+    }
+    return Some(nsCString(mUtf8));
+  }
+};
+
+class PresentationData {
+  NS_INLINE_DECL_REFCOUNTING(PresentationData);
+
+ public:
+  RawId mDeviceId = 0;
+  RawId mQueueId = 0;
+  layers::RGBDescriptor mDesc;
+  uint32_t mSourcePitch = 0;
+  int32_t mNextFrameID = 1;
+  std::vector<RawId> mUnassignedBufferIds MOZ_GUARDED_BY(mBuffersLock);
+  std::vector<RawId> mAvailableBufferIds MOZ_GUARDED_BY(mBuffersLock);
+  std::vector<RawId> mQueuedBufferIds MOZ_GUARDED_BY(mBuffersLock);
+  Mutex mBuffersLock;
+
+  PresentationData(RawId aDeviceId, RawId aQueueId,
+                   const layers::RGBDescriptor& aDesc, uint32_t aSourcePitch,
+                   const nsTArray<RawId>& aBufferIds)
+      : mDeviceId(aDeviceId),
+        mQueueId(aQueueId),
+        mDesc(aDesc),
+        mSourcePitch(aSourcePitch),
+        mBuffersLock("WebGPU presentation buffers") {
+    MOZ_COUNT_CTOR(PresentationData);
+
+    for (const RawId id : aBufferIds) {
+      mUnassignedBufferIds.push_back(id);
+    }
+  }
+
+ private:
+  ~PresentationData() { MOZ_COUNT_DTOR(PresentationData); }
+};
+
+static void FreeAdapter(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_adapter_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeAdapter");
+  }
+}
+static void FreeDevice(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_device_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeDevice");
+  }
+}
+static void FreeShaderModule(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_shader_module_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeShaderModule");
+  }
+}
+static void FreePipelineLayout(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_pipeline_layout_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreePipelineLayout");
+  }
+}
+static void FreeBindGroupLayout(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_bind_group_layout_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeBindGroupLayout");
+  }
+}
+static void FreeBindGroup(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_bind_group_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeBindGroup");
+  }
+}
+static void FreeCommandBuffer(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_command_buffer_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeCommandBuffer");
+  }
+}
+static void FreeRenderBundle(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_render_bundle_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeRenderBundle");
+  }
+}
+static void FreeRenderPipeline(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_render_pipeline_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeRenderPipeline");
+  }
+}
+static void FreeComputePipeline(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_compute_pipeline_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeComputePipeline");
+  }
+}
+static void FreeBuffer(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_buffer_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeBuffer");
+  }
+}
+static void FreeTexture(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_texture_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeTexture");
+  }
+}
+static void FreeTextureView(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_texture_view_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeTextureView");
+  }
+}
+static void FreeSampler(RawId id, void* param) {
+  ipc::ByteBuf byteBuf;
+  wgpu_server_sampler_free(id, ToFFI(&byteBuf));
+  if (!static_cast<WebGPUParent*>(param)->SendDropAction(std::move(byteBuf))) {
+    NS_ERROR("Unable FreeSampler");
+  }
+}
+static void FreeSurface(RawId id, void* param) {
+  Unused << id;
+  Unused << param;
+}
+
+static ffi::WGPUIdentityRecyclerFactory MakeFactory(void* param) {
+  ffi::WGPUIdentityRecyclerFactory factory;
+  PodZero(&factory);
+  factory.param = param;
+  factory.free_adapter = FreeAdapter;
+  factory.free_device = FreeDevice;
+  factory.free_pipeline_layout = FreePipelineLayout;
+  factory.free_shader_module = FreeShaderModule;
+  factory.free_bind_group_layout = FreeBindGroupLayout;
+  factory.free_bind_group = FreeBindGroup;
+  factory.free_command_buffer = FreeCommandBuffer;
+  factory.free_render_bundle = FreeRenderBundle;
+  factory.free_render_pipeline = FreeRenderPipeline;
+  factory.free_compute_pipeline = FreeComputePipeline;
+  factory.free_buffer = FreeBuffer;
+  factory.free_texture = FreeTexture;
+  factory.free_texture_view = FreeTextureView;
+  factory.free_sampler = FreeSampler;
+  factory.free_surface = FreeSurface;
+  return factory;
+}
+
+WebGPUParent::WebGPUParent()
+    : mContext(ffi::wgpu_server_new(MakeFactory(this))) {
+  mTimer.Start(base::TimeDelta::FromMilliseconds(POLL_TIME_MS), this,
+               &WebGPUParent::MaintainDevices);
+}
+
+WebGPUParent::~WebGPUParent() = default;
+
+void WebGPUParent::MaintainDevices() {
+  ffi::wgpu_server_poll_all_devices(mContext.get(), false);
+}
+
+bool WebGPUParent::ForwardError(RawId aDeviceId, ErrorBuffer& aError) {
+  // don't do anything if the error is empty
+  auto cString = aError.GetError();
+  if (!cString) {
+    return false;
+  }
+
+  ReportError(aDeviceId, cString.value());
+
+  return true;
+}
+
+// Generate an error on the Device timeline of aDeviceId.
+// aMessage is interpreted as UTF-8.
+void WebGPUParent::ReportError(RawId aDeviceId, const nsCString& aMessage) {
+  // find the appropriate error scope
+  const auto& lookup = mErrorScopeMap.find(aDeviceId);
+  if (lookup != mErrorScopeMap.end() && !lookup->second.mStack.IsEmpty()) {
+    auto& last = lookup->second.mStack.LastElement();
+    if (last.isNothing()) {
+      last.emplace(ScopedError{false, aMessage});
+    }
+  } else {
+    // fall back to the uncaptured error handler
+    if (!SendDeviceUncapturedError(aDeviceId, aMessage)) {
+      NS_ERROR("Unable to SendError");
+    }
+  }
+}
+
+ipc::IPCResult WebGPUParent::RecvInstanceRequestAdapter(
+    const dom::GPURequestAdapterOptions& aOptions,
+    const nsTArray<RawId>& aTargetIds,
+    InstanceRequestAdapterResolver&& resolver) {
+  ffi::WGPURequestAdapterOptions options = {};
+  if (aOptions.mPowerPreference.WasPassed()) {
+    options.power_preference = static_cast<ffi::WGPUPowerPreference>(
+        aOptions.mPowerPreference.Value());
+  }
+  options.force_fallback_adapter = aOptions.mForceFallbackAdapter;
+
+  ErrorBuffer error;
+  int8_t index = ffi::wgpu_server_instance_request_adapter(
+      mContext.get(), &options, aTargetIds.Elements(), aTargetIds.Length(),
+      error.ToFFI());
+
+  ByteBuf infoByteBuf;
+  // Rust side expects an `Option`, so 0 maps to `None`.
+  uint64_t adapterId = 0;
+  if (index >= 0) {
+    adapterId = aTargetIds[index];
+  }
+  ffi::wgpu_server_adapter_pack_info(mContext.get(), adapterId,
+                                     ToFFI(&infoByteBuf));
+  resolver(std::move(infoByteBuf));
+  ForwardError(0, error);
+
+  // free the unused IDs
+  ipc::ByteBuf dropByteBuf;
+  for (size_t i = 0; i < aTargetIds.Length(); ++i) {
+    if (static_cast<int8_t>(i) != index) {
+      wgpu_server_adapter_free(aTargetIds[i], ToFFI(&dropByteBuf));
+    }
+  }
+  if (dropByteBuf.mData && !SendDropAction(std::move(dropByteBuf))) {
+    NS_ERROR("Unable to free free unused adapter IDs");
+  }
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvAdapterRequestDevice(
+    RawId aAdapterId, const ipc::ByteBuf& aByteBuf, RawId aDeviceId,
+    AdapterRequestDeviceResolver&& resolver) {
+  ErrorBuffer error;
+  ffi::wgpu_server_adapter_request_device(
+      mContext.get(), aAdapterId, ToFFI(&aByteBuf), aDeviceId, error.ToFFI());
+  if (ForwardError(0, error)) {
+    resolver(false);
+  } else {
+    mErrorScopeMap.insert({aAdapterId, ErrorScopeStack()});
+    resolver(true);
+  }
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvAdapterDestroy(RawId aAdapterId) {
+  ffi::wgpu_server_adapter_drop(mContext.get(), aAdapterId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvDeviceDestroy(RawId aDeviceId) {
+  ffi::wgpu_server_device_drop(mContext.get(), aDeviceId);
+  mErrorScopeMap.erase(aDeviceId);
+  return IPC_OK();
+}
+
+WebGPUParent::BufferMapData* WebGPUParent::GetBufferMapData(RawId aBufferId) {
+  const auto iter = mSharedMemoryMap.find(aBufferId);
+  if (iter == mSharedMemoryMap.end()) {
+    return nullptr;
+  }
+
+  return &iter->second;
+}
+
+ipc::IPCResult WebGPUParent::RecvCreateBuffer(
+    RawId aDeviceId, RawId aBufferId, dom::GPUBufferDescriptor&& aDesc,
+    ipc::UnsafeSharedMemoryHandle&& aShmem) {
+  webgpu::StringHelper label(aDesc.mLabel);
+
+  auto shmem =
+      ipc::WritableSharedMemoryMapping::Open(std::move(aShmem)).value();
+
+  bool hasMapFlags = aDesc.mUsage & (dom::GPUBufferUsage_Binding::MAP_WRITE |
+                                     dom::GPUBufferUsage_Binding::MAP_READ);
+  if (hasMapFlags || aDesc.mMappedAtCreation) {
+    uint64_t offset = 0;
+    uint64_t size = 0;
+    if (aDesc.mMappedAtCreation) {
+      size = aDesc.mSize;
+      MOZ_RELEASE_ASSERT(shmem.Size() >= aDesc.mSize);
+    }
+
+    BufferMapData data = {std::move(shmem), hasMapFlags, offset, size};
+    mSharedMemoryMap.insert({aBufferId, std::move(data)});
+  }
+
+  ErrorBuffer error;
+  ffi::wgpu_server_device_create_buffer(mContext.get(), aDeviceId, aBufferId,
+                                        label.Get(), aDesc.mSize, aDesc.mUsage,
+                                        aDesc.mMappedAtCreation, error.ToFFI());
+  ForwardError(aDeviceId, error);
+  return IPC_OK();
+}
+
+struct MapRequest {
+  RefPtr<WebGPUParent> mParent;
+  ffi::WGPUGlobal* mContext;
+  ffi::WGPUBufferId mBufferId;
+  ffi::WGPUHostMap mHostMap;
+  uint64_t mOffset;
+  uint64_t mSize;
+  WebGPUParent::BufferMapResolver mResolver;
+};
+
+static const char* MapStatusString(ffi::WGPUBufferMapAsyncStatus status) {
+  switch (status) {
+    case ffi::WGPUBufferMapAsyncStatus_Success:
+      return "Success";
+    case ffi::WGPUBufferMapAsyncStatus_AlreadyMapped:
+      return "Already mapped";
+    case ffi::WGPUBufferMapAsyncStatus_MapAlreadyPending:
+      return "Map is already pending";
+    case ffi::WGPUBufferMapAsyncStatus_Aborted:
+      return "Map aborted";
+    case ffi::WGPUBufferMapAsyncStatus_ContextLost:
+      return "Context lost";
+    case ffi::WGPUBufferMapAsyncStatus_Invalid:
+      return "Invalid buffer";
+    case ffi::WGPUBufferMapAsyncStatus_InvalidRange:
+      return "Invalid range";
+    case ffi::WGPUBufferMapAsyncStatus_InvalidAlignment:
+      return "Invalid alignment";
+    case ffi::WGPUBufferMapAsyncStatus_InvalidUsageFlags:
+      return "Invalid usage flags";
+    case ffi::WGPUBufferMapAsyncStatus_Error:
+      return "Map failed";
+    case ffi::WGPUBufferMapAsyncStatus_Sentinel:  // For -Wswitch
+      break;
+  }
+
+  MOZ_CRASH("Bad ffi::WGPUBufferMapAsyncStatus");
+}
+
+static void MapCallback(ffi::WGPUBufferMapAsyncStatus status,
+                        uint8_t* userdata) {
+  auto* req = reinterpret_cast<MapRequest*>(userdata);
+
+  if (!req->mParent->CanSend()) {
+    delete req;
+    return;
+  }
+
+  BufferMapResult result;
+
+  auto bufferId = req->mBufferId;
+  auto* mapData = req->mParent->GetBufferMapData(bufferId);
+  MOZ_RELEASE_ASSERT(mapData);
+
+  if (status != ffi::WGPUBufferMapAsyncStatus_Success) {
+    result = BufferMapError(nsPrintfCString("Mapping WebGPU buffer failed: %s",
+                                            MapStatusString(status)));
+  } else {
+    auto size = req->mSize;
+    auto offset = req->mOffset;
+
+    if (req->mHostMap == ffi::WGPUHostMap_Read && size > 0) {
+      const auto src = ffi::wgpu_server_buffer_get_mapped_range(
+          req->mContext, req->mBufferId, offset, size);
+
+      MOZ_RELEASE_ASSERT(mapData->mShmem.Size() >= offset + size);
+      if (src.ptr != nullptr && src.length >= size) {
+        auto dst = mapData->mShmem.Bytes().Subspan(offset, size);
+        memcpy(dst.data(), src.ptr, size);
+      }
+    }
+
+    result =
+        BufferMapSuccess(offset, size, req->mHostMap == ffi::WGPUHostMap_Write);
+
+    mapData->mMappedOffset = offset;
+    mapData->mMappedSize = size;
+  }
+
+  req->mResolver(std::move(result));
+  delete req;
+}
+
+ipc::IPCResult WebGPUParent::RecvBufferMap(RawId aBufferId, uint32_t aMode,
+                                           uint64_t aOffset, uint64_t aSize,
+                                           BufferMapResolver&& aResolver) {
+  MOZ_LOG(sLogger, LogLevel::Info,
+          ("RecvBufferMap %" PRIu64 " offset=%" PRIu64 " size=%" PRIu64 "\n",
+           aBufferId, aOffset, aSize));
+
+  ffi::WGPUHostMap mode;
+  switch (aMode) {
+    case dom::GPUMapMode_Binding::READ:
+      mode = ffi::WGPUHostMap_Read;
+      break;
+    case dom::GPUMapMode_Binding::WRITE:
+      mode = ffi::WGPUHostMap_Write;
+      break;
+    default: {
+      nsCString errorString(
+          "GPUBuffer.mapAsync 'mode' argument must be either GPUMapMode.READ "
+          "or GPUMapMode.WRITE");
+      aResolver(BufferMapError(errorString));
+      return IPC_OK();
+    }
+  }
+
+  auto* mapData = GetBufferMapData(aBufferId);
+
+  if (!mapData) {
+    nsCString errorString("Buffer is not mappable");
+    aResolver(BufferMapError(errorString));
+    return IPC_OK();
+  }
+
+  auto* request =
+      new MapRequest{this,    mContext.get(), aBufferId,           mode,
+                     aOffset, aSize,          std::move(aResolver)};
+
+  ffi::WGPUBufferMapCallbackC callback = {&MapCallback,
+                                          reinterpret_cast<uint8_t*>(request)};
+  ffi::wgpu_server_buffer_map(mContext.get(), aBufferId, aOffset, aSize, mode,
+                              callback);
+
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvBufferUnmap(RawId aDeviceId, RawId aBufferId,
+                                             bool aFlush) {
+  MOZ_LOG(sLogger, LogLevel::Info,
+          ("RecvBufferUnmap %" PRIu64 " flush=%d\n", aBufferId, aFlush));
+
+  auto* mapData = GetBufferMapData(aBufferId);
+
+  if (mapData && aFlush) {
+    uint64_t offset = mapData->mMappedOffset;
+    uint64_t size = mapData->mMappedSize;
+
+    const auto mapped = ffi::wgpu_server_buffer_get_mapped_range(
+        mContext.get(), aBufferId, offset, size);
+
+    if (mapped.ptr != nullptr && mapped.length >= size) {
+      auto shmSize = mapData->mShmem.Size();
+      MOZ_RELEASE_ASSERT(offset <= shmSize);
+      MOZ_RELEASE_ASSERT(size <= shmSize - offset);
+
+      auto src = mapData->mShmem.Bytes().Subspan(offset, size);
+      memcpy(mapped.ptr, src.data(), size);
+    }
+
+    mapData->mMappedOffset = 0;
+    mapData->mMappedSize = 0;
+  }
+
+  ErrorBuffer error;
+  ffi::wgpu_server_buffer_unmap(mContext.get(), aBufferId, error.ToFFI());
+  ForwardError(aDeviceId, error);
+
+  if (mapData && !mapData->mHasMapFlags) {
+    // We get here if the buffer was mapped at creation without map flags.
+    // We don't need the shared memory anymore.
+    DeallocBufferShmem(aBufferId);
+  }
+
+  return IPC_OK();
+}
+
+void WebGPUParent::DeallocBufferShmem(RawId aBufferId) {
+  const auto iter = mSharedMemoryMap.find(aBufferId);
+  if (iter != mSharedMemoryMap.end()) {
+    mSharedMemoryMap.erase(iter);
+  }
+}
+
+ipc::IPCResult WebGPUParent::RecvBufferDrop(RawId aBufferId) {
+  ffi::wgpu_server_buffer_drop(mContext.get(), aBufferId);
+  MOZ_LOG(sLogger, LogLevel::Info, ("RecvBufferDrop %" PRIu64 "\n", aBufferId));
+
+  DeallocBufferShmem(aBufferId);
+
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvBufferDestroy(RawId aBufferId) {
+  ffi::wgpu_server_buffer_destroy(mContext.get(), aBufferId);
+  MOZ_LOG(sLogger, LogLevel::Info,
+          ("RecvBufferDestroy %" PRIu64 "\n", aBufferId));
+
+  DeallocBufferShmem(aBufferId);
+
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvTextureDestroy(RawId aTextureId) {
+  ffi::wgpu_server_texture_drop(mContext.get(), aTextureId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvTextureViewDestroy(RawId aTextureViewId) {
+  ffi::wgpu_server_texture_view_drop(mContext.get(), aTextureViewId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvSamplerDestroy(RawId aSamplerId) {
+  ffi::wgpu_server_sampler_drop(mContext.get(), aSamplerId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvCommandEncoderFinish(
+    RawId aEncoderId, RawId aDeviceId,
+    const dom::GPUCommandBufferDescriptor& aDesc) {
+  Unused << aDesc;
+  ffi::WGPUCommandBufferDescriptor desc = {};
+
+  webgpu::StringHelper label(aDesc.mLabel);
+  desc.label = label.Get();
+
+  ErrorBuffer error;
+  ffi::wgpu_server_encoder_finish(mContext.get(), aEncoderId, &desc,
+                                  error.ToFFI());
+
+  ForwardError(aDeviceId, error);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvCommandEncoderDestroy(RawId aEncoderId) {
+  ffi::wgpu_server_encoder_drop(mContext.get(), aEncoderId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvCommandBufferDestroy(RawId aCommandBufferId) {
+  ffi::wgpu_server_command_buffer_drop(mContext.get(), aCommandBufferId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvRenderBundleDestroy(RawId aBundleId) {
+  ffi::wgpu_server_render_bundle_drop(mContext.get(), aBundleId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvQueueSubmit(
+    RawId aQueueId, RawId aDeviceId, const nsTArray<RawId>& aCommandBuffers) {
+  ErrorBuffer error;
+  ffi::wgpu_server_queue_submit(mContext.get(), aQueueId,
+                                aCommandBuffers.Elements(),
+                                aCommandBuffers.Length(), error.ToFFI());
+  ForwardError(aDeviceId, error);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvQueueWriteAction(
+    RawId aQueueId, RawId aDeviceId, const ipc::ByteBuf& aByteBuf,
+    ipc::UnsafeSharedMemoryHandle&& aShmem) {
+  auto mapping =
+      ipc::WritableSharedMemoryMapping::Open(std::move(aShmem)).value();
+
+  ErrorBuffer error;
+  ffi::wgpu_server_queue_write_action(mContext.get(), aQueueId,
+                                      ToFFI(&aByteBuf), mapping.Bytes().data(),
+                                      mapping.Size(), error.ToFFI());
+  ForwardError(aDeviceId, error);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvBindGroupLayoutDestroy(RawId aBindGroupId) {
+  ffi::wgpu_server_bind_group_layout_drop(mContext.get(), aBindGroupId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvPipelineLayoutDestroy(RawId aLayoutId) {
+  ffi::wgpu_server_pipeline_layout_drop(mContext.get(), aLayoutId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvBindGroupDestroy(RawId aBindGroupId) {
+  ffi::wgpu_server_bind_group_drop(mContext.get(), aBindGroupId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvShaderModuleDestroy(RawId aModuleId) {
+  ffi::wgpu_server_shader_module_drop(mContext.get(), aModuleId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvComputePipelineDestroy(RawId aPipelineId) {
+  ffi::wgpu_server_compute_pipeline_drop(mContext.get(), aPipelineId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvRenderPipelineDestroy(RawId aPipelineId) {
+  ffi::wgpu_server_render_pipeline_drop(mContext.get(), aPipelineId);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvImplicitLayoutDestroy(
+    RawId aImplicitPlId, const nsTArray<RawId>& aImplicitBglIds) {
+  ffi::wgpu_server_pipeline_layout_drop(mContext.get(), aImplicitPlId);
+  for (const auto& id : aImplicitBglIds) {
+    ffi::wgpu_server_bind_group_layout_drop(mContext.get(), id);
+  }
+  return IPC_OK();
+}
+
+// TODO: proper destruction
+
+ipc::IPCResult WebGPUParent::RecvDeviceCreateSwapChain(
+    RawId aDeviceId, RawId aQueueId, const RGBDescriptor& aDesc,
+    const nsTArray<RawId>& aBufferIds,
+    const layers::RemoteTextureOwnerId& aOwnerId) {
+  switch (aDesc.format()) {
+    case gfx::SurfaceFormat::R8G8B8A8:
+    case gfx::SurfaceFormat::B8G8R8A8:
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid surface format!");
+      return IPC_OK();
+  }
+
+  constexpr uint32_t kBufferAlignmentMask = 0xff;
+  const auto bufferStrideWithMask = CheckedInt<uint32_t>(aDesc.size().width) *
+                                        gfx::BytesPerPixel(aDesc.format()) +
+                                    kBufferAlignmentMask;
+  if (!bufferStrideWithMask.isValid()) {
+    MOZ_ASSERT_UNREACHABLE("Invalid width / buffer stride!");
+    return IPC_OK();
+  }
+
+  const uint32_t bufferStride =
+      bufferStrideWithMask.value() & ~kBufferAlignmentMask;
+
+  const auto rows = CheckedInt<uint32_t>(aDesc.size().height);
+  if (!rows.isValid()) {
+    MOZ_ASSERT_UNREACHABLE("Invalid height!");
+    return IPC_OK();
+  }
+
+  if (!mRemoteTextureOwner) {
+    mRemoteTextureOwner =
+        MakeRefPtr<layers::RemoteTextureOwnerClient>(OtherPid());
+  }
+  // RemoteTextureMap::GetRemoteTextureForDisplayList() works synchronously.
+  mRemoteTextureOwner->RegisterTextureOwner(aOwnerId, /* aIsSyncMode */ true);
+
+  auto data = MakeRefPtr<PresentationData>(aDeviceId, aQueueId, aDesc,
+                                           bufferStride, aBufferIds);
+  if (!mCanvasMap.emplace(aOwnerId, data).second) {
+    NS_ERROR("External image is already registered as WebGPU canvas!");
+  }
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvDeviceCreateShaderModule(
+    RawId aDeviceId, RawId aModuleId, const nsString& aLabel,
+    const nsCString& aCode, DeviceCreateShaderModuleResolver&& aOutMessage) {
+  // TODO: this should probably be an optional label in the IPC message.
+  const nsACString* label = nullptr;
+  NS_ConvertUTF16toUTF8 utf8Label(aLabel);
+  if (!utf8Label.IsEmpty()) {
+    label = &utf8Label;
+  }
+
+  ffi::WGPUShaderModuleCompilationMessage message;
+
+  bool ok = ffi::wgpu_server_device_create_shader_module(
+      mContext.get(), aDeviceId, aModuleId, label, &aCode, &message);
+
+  nsTArray<WebGPUCompilationMessage> messages;
+
+  if (!ok) {
+    WebGPUCompilationMessage msg;
+    msg.lineNum = message.line_number;
+    msg.linePos = message.line_pos;
+    msg.offset = message.utf16_offset;
+    msg.length = message.utf16_length;
+    msg.message = message.message;
+    // wgpu currently only returns errors.
+    msg.messageType = WebGPUCompilationMessageType::Error;
+
+    messages.AppendElement(msg);
+  }
+
+  aOutMessage(messages);
+
+  return IPC_OK();
+}
+
+struct PresentRequest {
+  PresentRequest(const ffi::WGPUGlobal* aContext,
+                 RefPtr<PresentationData>& aData,
+                 RefPtr<layers::RemoteTextureOwnerClient>& aRemoteTextureOwner,
+                 const layers::RemoteTextureId aTextureId,
+                 const layers::RemoteTextureOwnerId aOwnerId)
+      : mContext(aContext),
+        mData(aData),
+        mRemoteTextureOwner(aRemoteTextureOwner),
+        mTextureId(aTextureId),
+        mOwnerId(aOwnerId) {}
+
+  const ffi::WGPUGlobal* mContext;
+  RefPtr<PresentationData> mData;
+  RefPtr<layers::RemoteTextureOwnerClient> mRemoteTextureOwner;
+  const layers::RemoteTextureId mTextureId;
+  const layers::RemoteTextureOwnerId mOwnerId;
+};
+
+static void PresentCallback(ffi::WGPUBufferMapAsyncStatus status,
+                            uint8_t* userdata) {
+  UniquePtr<PresentRequest> req(reinterpret_cast<PresentRequest*>(userdata));
+
+  if (!req->mRemoteTextureOwner->IsRegistered(req->mOwnerId)) {
+    // SwapChain is already Destroyed
+    return;
+  }
+
+  PresentationData* data = req->mData.get();
+  // get the buffer ID
+  RawId bufferId;
+  {
+    MutexAutoLock lock(data->mBuffersLock);
+    bufferId = data->mQueuedBufferIds.back();
+    data->mQueuedBufferIds.pop_back();
+  }
+
+  // Ensure we'll make the bufferId available for reuse
+  auto releaseBuffer = MakeScopeExit([data = RefPtr{data}, bufferId] {
+    MutexAutoLock lock(data->mBuffersLock);
+    data->mAvailableBufferIds.push_back(bufferId);
+  });
+
+  MOZ_LOG(
+      sLogger, LogLevel::Info,
+      ("PresentCallback for buffer %" PRIu64 " status=%d\n", bufferId, status));
+  // copy the data
+  if (status == ffi::WGPUBufferMapAsyncStatus_Success) {
+    const auto bufferSize = data->mDesc.size().height * data->mSourcePitch;
+    const auto mapped = ffi::wgpu_server_buffer_get_mapped_range(
+        req->mContext, bufferId, 0, bufferSize);
+    MOZ_ASSERT(mapped.length >= bufferSize);
+    auto textureData =
+        req->mRemoteTextureOwner->CreateOrRecycleBufferTextureData(
+            req->mOwnerId, data->mDesc.size(), data->mDesc.format());
+    if (!textureData) {
+      gfxCriticalNoteOnce << "Failed to allocate BufferTextureData";
+      return;
+    }
+    layers::MappedTextureData mappedData;
+    if (textureData && textureData->BorrowMappedData(mappedData)) {
+      uint8_t* src = mapped.ptr;
+      uint8_t* dst = mappedData.data;
+      for (auto row = 0; row < data->mDesc.size().height; ++row) {
+        memcpy(dst, src, mappedData.stride);
+        dst += mappedData.stride;
+        src += data->mSourcePitch;
+      }
+      req->mRemoteTextureOwner->PushTexture(req->mTextureId, req->mOwnerId,
+                                            std::move(textureData),
+                                            /* aSharedSurface */ nullptr);
+    } else {
+      NS_WARNING("WebGPU present skipped: the swapchain is resized!");
+    }
+    ErrorBuffer error;
+    wgpu_server_buffer_unmap(req->mContext, bufferId, error.ToFFI());
+    if (auto errorString = error.GetError()) {
+      MOZ_LOG(
+          sLogger, LogLevel::Info,
+          ("WebGPU present: buffer unmap failed: %s\n", errorString->get()));
+    }
+  } else {
+    // TODO: better handle errors
+    NS_WARNING("WebGPU frame mapping failed!");
+  }
+}
+
+ipc::IPCResult WebGPUParent::GetFrontBufferSnapshot(
+    IProtocol* aProtocol, const layers::RemoteTextureOwnerId& aOwnerId,
+    Maybe<Shmem>& aShmem, gfx::IntSize& aSize) {
+  const auto& lookup = mCanvasMap.find(aOwnerId);
+  if (lookup == mCanvasMap.end() || !mRemoteTextureOwner) {
+    return IPC_OK();
+  }
+
+  RefPtr<PresentationData> data = lookup->second.get();
+  aSize = data->mDesc.size();
+  uint32_t stride = layers::ImageDataSerializer::ComputeRGBStride(
+      data->mDesc.format(), aSize.width);
+  uint32_t len = data->mDesc.size().height * stride;
+  Shmem shmem;
+  if (!AllocShmem(len, &shmem)) {
+    return IPC_OK();
+  }
+
+  mRemoteTextureOwner->GetLatestBufferSnapshot(aOwnerId, shmem, aSize);
+  aShmem.emplace(std::move(shmem));
+
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvSwapChainPresent(
+    RawId aTextureId, RawId aCommandEncoderId,
+    const layers::RemoteTextureId& aRemoteTextureId,
+    const layers::RemoteTextureOwnerId& aOwnerId) {
+  // step 0: get the data associated with the swapchain
+  const auto& lookup = mCanvasMap.find(aOwnerId);
+  if (lookup == mCanvasMap.end() || !mRemoteTextureOwner ||
+      !mRemoteTextureOwner->IsRegistered(aOwnerId)) {
+    NS_WARNING("WebGPU presenting on a destroyed swap chain!");
+    return IPC_OK();
+  }
+
+  RefPtr<PresentationData> data = lookup->second.get();
+  RawId bufferId = 0;
+  const auto& size = data->mDesc.size();
+  const auto bufferSize = data->mDesc.size().height * data->mSourcePitch;
+
+  // step 1: find an available staging buffer, or create one
+  {
+    MutexAutoLock lock(data->mBuffersLock);
+    if (!data->mAvailableBufferIds.empty()) {
+      bufferId = data->mAvailableBufferIds.back();
+      data->mAvailableBufferIds.pop_back();
+    } else if (!data->mUnassignedBufferIds.empty()) {
+      bufferId = data->mUnassignedBufferIds.back();
+      data->mUnassignedBufferIds.pop_back();
+
+      ffi::WGPUBufferUsages usage =
+          WGPUBufferUsages_COPY_DST | WGPUBufferUsages_MAP_READ;
+
+      ErrorBuffer error;
+      ffi::wgpu_server_device_create_buffer(mContext.get(), data->mDeviceId,
+                                            bufferId, nullptr, bufferSize,
+                                            usage, false, error.ToFFI());
+      if (ForwardError(data->mDeviceId, error)) {
+        return IPC_OK();
+      }
+    } else {
+      bufferId = 0;
+    }
+
+    if (bufferId) {
+      data->mQueuedBufferIds.insert(data->mQueuedBufferIds.begin(), bufferId);
+    }
+  }
+
+  MOZ_LOG(sLogger, LogLevel::Info,
+          ("RecvSwapChainPresent with buffer %" PRIu64 "\n", bufferId));
+  if (!bufferId) {
+    // TODO: add a warning - no buffer are available!
+    return IPC_OK();
+  }
+
+  // step 3: submit a copy command for the frame
+  ffi::WGPUCommandEncoderDescriptor encoderDesc = {};
+  {
+    ErrorBuffer error;
+    ffi::wgpu_server_device_create_encoder(mContext.get(), data->mDeviceId,
+                                           &encoderDesc, aCommandEncoderId,
+                                           error.ToFFI());
+    if (ForwardError(data->mDeviceId, error)) {
+      return IPC_OK();
+    }
+  }
+
+  const ffi::WGPUImageCopyTexture texView = {
+      aTextureId,
+  };
+  const ffi::WGPUImageDataLayout bufLayout = {
+      0,
+      &data->mSourcePitch,
+      nullptr,
+  };
+  const ffi::WGPUExtent3d extent = {
+      static_cast<uint32_t>(size.width),
+      static_cast<uint32_t>(size.height),
+      1,
+  };
+  ffi::wgpu_server_encoder_copy_texture_to_buffer(
+      mContext.get(), aCommandEncoderId, &texView, bufferId, &bufLayout,
+      &extent);
+  ffi::WGPUCommandBufferDescriptor commandDesc = {};
+  {
+    ErrorBuffer error;
+    ffi::wgpu_server_encoder_finish(mContext.get(), aCommandEncoderId,
+                                    &commandDesc, error.ToFFI());
+    if (ForwardError(data->mDeviceId, error)) {
+      return IPC_OK();
+    }
+  }
+
+  {
+    ErrorBuffer error;
+    ffi::wgpu_server_queue_submit(mContext.get(), data->mQueueId,
+                                  &aCommandEncoderId, 1, error.ToFFI());
+    if (ForwardError(data->mDeviceId, error)) {
+      return IPC_OK();
+    }
+  }
+
+  // step 4: request the pixels to be copied into the external texture
+  // TODO: this isn't strictly necessary. When WR wants to Lock() the external
+  // texture,
+  // we can just give it the contents of the last mapped buffer instead of the
+  // copy.
+  auto presentRequest = MakeUnique<PresentRequest>(
+      mContext.get(), data, mRemoteTextureOwner, aRemoteTextureId, aOwnerId);
+
+  ffi::WGPUBufferMapCallbackC callback = {
+      &PresentCallback, reinterpret_cast<uint8_t*>(presentRequest.release())};
+  ffi::wgpu_server_buffer_map(mContext.get(), bufferId, 0, bufferSize,
+                              ffi::WGPUHostMap_Read, callback);
+
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvSwapChainDestroy(
+    const layers::RemoteTextureOwnerId& aOwnerId) {
+  if (mRemoteTextureOwner) {
+    mRemoteTextureOwner->UnregisterTextureOwner(aOwnerId);
+  }
+  const auto& lookup = mCanvasMap.find(aOwnerId);
+  MOZ_ASSERT(lookup != mCanvasMap.end());
+  if (lookup == mCanvasMap.end()) {
+    NS_WARNING("WebGPU presenting on a destroyed swap chain!");
+    return IPC_OK();
+  }
+
+  RefPtr<PresentationData> data = lookup->second.get();
+  mCanvasMap.erase(lookup);
+
+  MutexAutoLock lock(data->mBuffersLock);
+  ipc::ByteBuf dropByteBuf;
+  for (const auto bid : data->mUnassignedBufferIds) {
+    wgpu_server_buffer_free(bid, ToFFI(&dropByteBuf));
+  }
+  if (dropByteBuf.mData && !SendDropAction(std::move(dropByteBuf))) {
+    NS_WARNING("Unable to free an ID for non-assigned buffer");
+  }
+  for (const auto bid : data->mAvailableBufferIds) {
+    ffi::wgpu_server_buffer_drop(mContext.get(), bid);
+  }
+  for (const auto bid : data->mQueuedBufferIds) {
+    ffi::wgpu_server_buffer_drop(mContext.get(), bid);
+  }
+  return IPC_OK();
+}
+
+void WebGPUParent::ActorDestroy(ActorDestroyReason aWhy) {
+  mTimer.Stop();
+  mCanvasMap.clear();
+  if (mRemoteTextureOwner) {
+    mRemoteTextureOwner->UnregisterAllTextureOwners();
+    mRemoteTextureOwner = nullptr;
+  }
+  ffi::wgpu_server_poll_all_devices(mContext.get(), true);
+  mContext = nullptr;
+}
+
+ipc::IPCResult WebGPUParent::RecvDeviceAction(RawId aDeviceId,
+                                              const ipc::ByteBuf& aByteBuf) {
+  ErrorBuffer error;
+  ffi::wgpu_server_device_action(mContext.get(), aDeviceId, ToFFI(&aByteBuf),
+                                 error.ToFFI());
+
+  ForwardError(aDeviceId, error);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvDeviceActionWithAck(
+    RawId aDeviceId, const ipc::ByteBuf& aByteBuf,
+    DeviceActionWithAckResolver&& aResolver) {
+  ErrorBuffer error;
+  ffi::wgpu_server_device_action(mContext.get(), aDeviceId, ToFFI(&aByteBuf),
+                                 error.ToFFI());
+
+  ForwardError(aDeviceId, error);
+  aResolver(true);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvTextureAction(RawId aTextureId,
+                                               RawId aDeviceId,
+                                               const ipc::ByteBuf& aByteBuf) {
+  ErrorBuffer error;
+  ffi::wgpu_server_texture_action(mContext.get(), aTextureId, ToFFI(&aByteBuf),
+                                  error.ToFFI());
+
+  ForwardError(aDeviceId, error);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvCommandEncoderAction(
+    RawId aEncoderId, RawId aDeviceId, const ipc::ByteBuf& aByteBuf) {
+  ErrorBuffer error;
+  ffi::wgpu_server_command_encoder_action(mContext.get(), aEncoderId,
+                                          ToFFI(&aByteBuf), error.ToFFI());
+  ForwardError(aDeviceId, error);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvBumpImplicitBindGroupLayout(RawId aPipelineId,
+                                                             bool aIsCompute,
+                                                             uint32_t aIndex,
+                                                             RawId aAssignId) {
+  ErrorBuffer error;
+  if (aIsCompute) {
+    ffi::wgpu_server_compute_pipeline_get_bind_group_layout(
+        mContext.get(), aPipelineId, aIndex, aAssignId, error.ToFFI());
+  } else {
+    ffi::wgpu_server_render_pipeline_get_bind_group_layout(
+        mContext.get(), aPipelineId, aIndex, aAssignId, error.ToFFI());
+  }
+
+  ForwardError(0, error);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvDevicePushErrorScope(RawId aDeviceId) {
+  const auto& lookup = mErrorScopeMap.find(aDeviceId);
+  if (lookup == mErrorScopeMap.end()) {
+    // Content can cause this simply by destroying a device and then
+    // calling `pushErrorScope`.
+    return IPC_OK();
+  }
+
+  lookup->second.mStack.EmplaceBack();
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvDevicePopErrorScope(
+    RawId aDeviceId, DevicePopErrorScopeResolver&& aResolver) {
+  const auto& lookup = mErrorScopeMap.find(aDeviceId);
+  if (lookup == mErrorScopeMap.end()) {
+    // Content can cause this simply by destroying a device and then
+    // calling `popErrorScope`.
+    ScopedError error = {true};
+    aResolver(Some(error));
+    return IPC_OK();
+  }
+
+  if (lookup->second.mStack.IsEmpty()) {
+    // Content can cause this simply by calling `popErrorScope` when
+    // there is no error scope pushed.
+    ScopedError error = {true};
+    aResolver(Some(error));
+    return IPC_OK();
+  }
+
+  auto scope = lookup->second.mStack.PopLastElement();
+  aResolver(scope);
+  return IPC_OK();
+}
+
+ipc::IPCResult WebGPUParent::RecvGenerateError(RawId aDeviceId,
+                                               const nsCString& aMessage) {
+  ReportError(aDeviceId, aMessage);
+  return IPC_OK();
+}
+
+}  // namespace mozilla::webgpu
diff --git a/dom/webgpu/ipc/WebGPUParent.h b/dom/webgpu/ipc/WebGPUParent.h
new file mode 100644
index 0000000000..384d560003
--- /dev/null
+++ b/dom/webgpu/ipc/WebGPUParent.h
@@ -0,0 +1,156 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WEBGPU_PARENT_H_
+#define WEBGPU_PARENT_H_
+
+#include "mozilla/webgpu/ffi/wgpu.h"
+#include "mozilla/webgpu/PWebGPUParent.h"
+#include "mozilla/webrender/WebRenderAPI.h"
+#include "mozilla/ipc/RawShmem.h"
+#include "WebGPUTypes.h"
+#include "base/timer.h"
+
+namespace mozilla {
+
+namespace layers {
+class RemoteTextureOwnerClient;
+}  // namespace layers
+
+namespace webgpu {
+
+class ErrorBuffer;
+class PresentationData;
+
+struct ErrorScopeStack {
+  nsTArray<MaybeScopedError> mStack;
+};
+
+class WebGPUParent final : public PWebGPUParent {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WebGPUParent, override)
+
+ public:
+  explicit WebGPUParent();
+
+  ipc::IPCResult RecvInstanceRequestAdapter(
+      const dom::GPURequestAdapterOptions& aOptions,
+      const nsTArray<RawId>& aTargetIds,
+      InstanceRequestAdapterResolver&& resolver);
+  ipc::IPCResult RecvAdapterRequestDevice(
+      RawId aAdapterId, const ipc::ByteBuf& aByteBuf, RawId aDeviceId,
+      AdapterRequestDeviceResolver&& resolver);
+  ipc::IPCResult RecvAdapterDestroy(RawId aAdapterId);
+  ipc::IPCResult RecvDeviceDestroy(RawId aDeviceId);
+  ipc::IPCResult RecvCreateBuffer(RawId aDeviceId, RawId aBufferId,
+                                  dom::GPUBufferDescriptor&& aDesc,
+                                  ipc::UnsafeSharedMemoryHandle&& aShmem);
+  ipc::IPCResult RecvBufferMap(RawId aBufferId, uint32_t aMode,
+                               uint64_t aOffset, uint64_t size,
+                               BufferMapResolver&& aResolver);
+  ipc::IPCResult RecvBufferUnmap(RawId aDeviceId, RawId aBufferId, bool aFlush);
+  ipc::IPCResult RecvBufferDestroy(RawId aBufferId);
+  ipc::IPCResult RecvBufferDrop(RawId aBufferId);
+  ipc::IPCResult RecvTextureDestroy(RawId aTextureId);
+  ipc::IPCResult RecvTextureViewDestroy(RawId aTextureViewId);
+  ipc::IPCResult RecvSamplerDestroy(RawId aSamplerId);
+  ipc::IPCResult RecvCommandEncoderFinish(
+      RawId aEncoderId, RawId aDeviceId,
+      const dom::GPUCommandBufferDescriptor& aDesc);
+  ipc::IPCResult RecvCommandEncoderDestroy(RawId aEncoderId);
+  ipc::IPCResult RecvCommandBufferDestroy(RawId aCommandBufferId);
+  ipc::IPCResult RecvRenderBundleDestroy(RawId aBundleId);
+  ipc::IPCResult RecvQueueSubmit(RawId aQueueId, RawId aDeviceId,
+                                 const nsTArray<RawId>& aCommandBuffers);
+  ipc::IPCResult RecvQueueWriteAction(RawId aQueueId, RawId aDeviceId,
+                                      const ipc::ByteBuf& aByteBuf,
+                                      ipc::UnsafeSharedMemoryHandle&& aShmem);
+  ipc::IPCResult RecvBindGroupLayoutDestroy(RawId aBindGroupLayoutId);
+  ipc::IPCResult RecvPipelineLayoutDestroy(RawId aPipelineLayoutId);
+  ipc::IPCResult RecvBindGroupDestroy(RawId aBindGroupId);
+  ipc::IPCResult RecvShaderModuleDestroy(RawId aModuleId);
+  ipc::IPCResult RecvComputePipelineDestroy(RawId aPipelineId);
+  ipc::IPCResult RecvRenderPipelineDestroy(RawId aPipelineId);
+  ipc::IPCResult RecvImplicitLayoutDestroy(
+      RawId aImplicitPlId, const nsTArray<RawId>& aImplicitBglIds);
+  ipc::IPCResult RecvDeviceCreateSwapChain(
+      RawId aDeviceId, RawId aQueueId, const layers::RGBDescriptor& aDesc,
+      const nsTArray<RawId>& aBufferIds,
+      const layers::RemoteTextureOwnerId& aOwnerId);
+  ipc::IPCResult RecvDeviceCreateShaderModule(
+      RawId aDeviceId, RawId aModuleId, const nsString& aLabel,
+      const nsCString& aCode, DeviceCreateShaderModuleResolver&& aOutMessage);
+
+  ipc::IPCResult RecvSwapChainPresent(
+      RawId aTextureId, RawId aCommandEncoderId,
+      const layers::RemoteTextureId& aRemoteTextureId,
+      const layers::RemoteTextureOwnerId& aOwnerId);
+  ipc::IPCResult RecvSwapChainDestroy(
+      const layers::RemoteTextureOwnerId& aOwnerId);
+
+  ipc::IPCResult RecvDeviceAction(RawId aDeviceId,
+                                  const ipc::ByteBuf& aByteBuf);
+  ipc::IPCResult RecvDeviceActionWithAck(
+      RawId aDeviceId, const ipc::ByteBuf& aByteBuf,
+      DeviceActionWithAckResolver&& aResolver);
+  ipc::IPCResult RecvTextureAction(RawId aTextureId, RawId aDevice,
+                                   const ipc::ByteBuf& aByteBuf);
+  ipc::IPCResult RecvCommandEncoderAction(RawId aEncoderId, RawId aDeviceId,
+                                          const ipc::ByteBuf& aByteBuf);
+  ipc::IPCResult RecvBumpImplicitBindGroupLayout(RawId aPipelineId,
+                                                 bool aIsCompute,
+                                                 uint32_t aIndex,
+                                                 RawId aAssignId);
+
+  ipc::IPCResult RecvDevicePushErrorScope(RawId aDeviceId);
+  ipc::IPCResult RecvDevicePopErrorScope(
+      RawId aDeviceId, DevicePopErrorScopeResolver&& aResolver);
+  ipc::IPCResult RecvGenerateError(RawId aDeviceId, const nsCString& message);
+
+  ipc::IPCResult GetFrontBufferSnapshot(
+      IProtocol* aProtocol, const layers::RemoteTextureOwnerId& aOwnerId,
+      Maybe<Shmem>& aShmem, gfx::IntSize& aSize);
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  struct BufferMapData {
+    ipc::WritableSharedMemoryMapping mShmem;
+    // True if buffer's usage has MAP_READ or MAP_WRITE set.
+    bool mHasMapFlags;
+    uint64_t mMappedOffset;
+    uint64_t mMappedSize;
+  };
+
+  BufferMapData* GetBufferMapData(RawId aBufferId);
+
+ private:
+  void DeallocBufferShmem(RawId aBufferId);
+
+  virtual ~WebGPUParent();
+  void MaintainDevices();
+  bool ForwardError(RawId aDeviceId, ErrorBuffer& aError);
+  void ReportError(RawId aDeviceId, const nsCString& message);
+
+  UniquePtr<ffi::WGPUGlobal> mContext;
+  base::RepeatingTimer<WebGPUParent> mTimer;
+
+  /// A map from wgpu buffer ids to data about their shared memory segments.
+  /// Includes entries about mappedAtCreation, MAP_READ and MAP_WRITE buffers,
+  /// regardless of their state.
+  std::unordered_map<uint64_t, BufferMapData> mSharedMemoryMap;
+  /// Associated presentation data for each swapchain.
+  std::unordered_map<layers::RemoteTextureOwnerId, RefPtr<PresentationData>,
+                     layers::RemoteTextureOwnerId::HashFn>
+      mCanvasMap;
+
+  RefPtr<layers::RemoteTextureOwnerClient> mRemoteTextureOwner;
+
+  /// Associated stack of error scopes for each device.
+  std::unordered_map<uint64_t, ErrorScopeStack> mErrorScopeMap;
+};
+
+}  // namespace webgpu
+}  // namespace mozilla
+
+#endif  // WEBGPU_PARENT_H_
diff --git a/dom/webgpu/ipc/WebGPUSerialize.h b/dom/webgpu/ipc/WebGPUSerialize.h
new file mode 100644
index 0000000000..b130fc992e
--- /dev/null
+++ b/dom/webgpu/ipc/WebGPUSerialize.h
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WEBGPU_SERIALIZE_H_
+#define WEBGPU_SERIALIZE_H_
+
+#include "WebGPUTypes.h"
+#include "ipc/EnumSerializer.h"
+#include "ipc/IPCMessageUtils.h"
+#include "mozilla/dom/WebGPUBinding.h"
+#include "mozilla/webgpu/ffi/wgpu.h"
+
+namespace IPC {
+
+#define DEFINE_IPC_SERIALIZER_ENUM_GUARD(something, guard) \
+  template <>                                              \
+  struct ParamTraits<something>                            \
+      : public ContiguousEnumSerializer<something, something(0), guard> {}
+
+#define DEFINE_IPC_SERIALIZER_DOM_ENUM(something) \
+  DEFINE_IPC_SERIALIZER_ENUM_GUARD(something, something::EndGuard_)
+#define DEFINE_IPC_SERIALIZER_FFI_ENUM(something) \
+  DEFINE_IPC_SERIALIZER_ENUM_GUARD(something, something##_Sentinel)
+
+DEFINE_IPC_SERIALIZER_DOM_ENUM(mozilla::dom::GPUPowerPreference);
+
+DEFINE_IPC_SERIALIZER_FFI_ENUM(mozilla::webgpu::ffi::WGPUHostMap);
+
+DEFINE_IPC_SERIALIZER_WITHOUT_FIELDS(mozilla::dom::GPUCommandBufferDescriptor);
+
+DEFINE_IPC_SERIALIZER_WITH_FIELDS(mozilla::dom::GPURequestAdapterOptions,
+                                  mPowerPreference, mForceFallbackAdapter);
+
+DEFINE_IPC_SERIALIZER_WITH_FIELDS(mozilla::dom::GPUBufferDescriptor, mSize,
+                                  mUsage, mMappedAtCreation);
+
+DEFINE_IPC_SERIALIZER_WITH_FIELDS(mozilla::webgpu::ScopedError, operationError,
+                                  validationMessage);
+
+DEFINE_IPC_SERIALIZER_WITH_FIELDS(mozilla::webgpu::WebGPUCompilationMessage,
+                                  message, lineNum, linePos);
+
+#undef DEFINE_IPC_SERIALIZER_FFI_ENUM
+#undef DEFINE_IPC_SERIALIZER_DOM_ENUM
+#undef DEFINE_IPC_SERIALIZER_ENUM_GUARD
+
+}  // namespace IPC
+#endif  // WEBGPU_SERIALIZE_H_
diff --git a/dom/webgpu/ipc/WebGPUTypes.h b/dom/webgpu/ipc/WebGPUTypes.h
new file mode 100644
index 0000000000..e607e03b99
--- /dev/null
+++ b/dom/webgpu/ipc/WebGPUTypes.h
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WEBGPU_TYPES_H_
+#define WEBGPU_TYPES_H_
+
+#include <cstdint>
+#include "mozilla/Maybe.h"
+#include "nsString.h"
+#include "mozilla/dom/BindingDeclarations.h"
+
+namespace mozilla::webgpu {
+
+using RawId = uint64_t;
+using BufferAddress = uint64_t;
+
+struct ScopedError {
+  // Did an error occur as a result the attempt to retrieve an error
+  // (e.g. from a dead device, from an empty scope stack)?
+  bool operationError = false;
+
+  // If non-empty, the first error generated when this scope was on
+  // the top of the stack. This is interpreted as UTF-8.
+  nsCString validationMessage;
+};
+using MaybeScopedError = Maybe<ScopedError>;
+
+enum class WebGPUCompilationMessageType { Error, Warning, Info };
+
+// TODO: Better name? CompilationMessage alread taken by the dom object.
+/// The serializable counterpart of the dom object CompilationMessage.
+struct WebGPUCompilationMessage {
+  nsString message;
+  uint64_t lineNum = 0;
+  uint64_t linePos = 0;
+  // In utf16 code units.
+  uint64_t offset = 0;
+  // In utf16 code units.
+  uint64_t length = 0;
+  WebGPUCompilationMessageType messageType =
+      WebGPUCompilationMessageType::Error;
+};
+
+/// A helper to reduce the boiler plate of turning the many Optional<nsAString>
+/// we get from the dom to the nullable nsACString* we pass to the wgpu ffi.
+class StringHelper {
+ public:
+  explicit StringHelper(const dom::Optional<nsString>& aWide) {
+    if (aWide.WasPassed()) {
+      mNarrow = Some(NS_ConvertUTF16toUTF8(aWide.Value()));
+    }
+  }
+
+  const nsACString* Get() const {
+    if (mNarrow.isSome()) {
+      return mNarrow.ptr();
+    }
+    return nullptr;
+  }
+
+ private:
+  Maybe<NS_ConvertUTF16toUTF8> mNarrow;
+};
+
+}  // namespace mozilla::webgpu
+
+#endif  // WEBGPU_TYPES_H_