[WebGPU] Do not require vertexInput in GPURenderPipelineDescriptor

Following WebGPU spec change at https://github.com/gpuweb/gpuweb/issues/378,
vertexInput descriptor from GPURenderPipelineDescriptor should not be
required anymore.

Bug: 877147
Change-Id: Ifdd0ba7ff6af2b8648ad45d029e5ef7b8484f8a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1776023
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691978}

third_party/blink/renderer/modules/webgpu/gpu_render_pipeline.cc

@@ -229,16 +229,22 @@ GPURenderPipeline* GPURenderPipeline::Create(
     dawn_desc.fragmentStage = nullptr;
   }
 
-  // TODO(crbug.com/dawn/131): Update Dawn to match WebGPU vertex input
-  v8::Isolate* isolate = script_state->GetIsolate();
-  ExceptionState exception_state(isolate, ExceptionState::kConstructionContext,
-                                 "GPUVertexInputDescriptor");
-  DawnVertexInputInfo vertex_input_info = GPUVertexInputAsDawnInputState(
-      isolate, webgpu_desc->vertexInput(), exception_state);
-  dawn_desc.vertexInput = &std::get<0>(vertex_input_info);
-
-  if (exception_state.HadException()) {
-    return nullptr;
+  DawnVertexInputInfo vertex_input_info;
+  if (webgpu_desc->hasVertexInput()) {
+    // TODO(crbug.com/dawn/131): Update Dawn to match WebGPU vertex input
+    v8::Isolate* isolate = script_state->GetIsolate();
+    ExceptionState exception_state(isolate,
+                                   ExceptionState::kConstructionContext,
+                                   "GPUVertexInputDescriptor");
+    vertex_input_info = GPUVertexInputAsDawnInputState(
+        isolate, webgpu_desc->vertexInput(), exception_state);
+    dawn_desc.vertexInput = &std::get<0>(vertex_input_info);
+
+    if (exception_state.HadException()) {
+      return nullptr;
+    }
+  } else {
+    dawn_desc.vertexInput = nullptr;
   }
 
   dawn_desc.primitiveTopology =

third_party/blink/renderer/modules/webgpu/gpu_render_pipeline_descriptor.idl

@@ -12,7 +12,7 @@ dictionary GPURenderPipelineDescriptor : GPUPipelineDescriptorBase {
     GPURasterizationStateDescriptor rasterizationState;
     required sequence<GPUColorStateDescriptor> colorStates;
     GPUDepthStencilStateDescriptor depthStencilState;
-    required GPUVertexInputDescriptor vertexInput;
+    GPUVertexInputDescriptor vertexInput;
 
     unsigned long sampleCount = 1;