[WebGPU] Consolidate *loadOp and clear* into a unioned field

Following WebGPU spec change at https://github.com/gpuweb/gpuweb/issues/283,
this CL makes sure *loadOp and clear* are consolidated into an unioned
field in GPURenderPassColorAttachmentDescriptor and
GPURenderPassDepthStencilAttachmentDescriptor.

Bug: 877147
Change-Id: I4a676e8cfa52844f2df54b6201e6db453c1d9e9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1715267Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#680373}

third_party/blink/renderer/bindings/modules/v8/generated.gni

@@ -48,6 +48,12 @@ bindings_modules_generated_union_type_files = [
   "$bindings_modules_v8_output_dir/float32_array_or_float64_array_or_dom_matrix.h",
   "$bindings_modules_v8_output_dir/gpu_out_of_memory_error_or_gpu_validation_error.cc",
   "$bindings_modules_v8_output_dir/gpu_out_of_memory_error_or_gpu_validation_error.h",
+  "$bindings_modules_v8_output_dir/gpu_load_op_or_gpu_color.cc",
+  "$bindings_modules_v8_output_dir/gpu_load_op_or_gpu_color.h",
+  "$bindings_modules_v8_output_dir/gpu_load_op_or_float.cc",
+  "$bindings_modules_v8_output_dir/gpu_load_op_or_float.h",
+  "$bindings_modules_v8_output_dir/gpu_load_op_or_long.cc",
+  "$bindings_modules_v8_output_dir/gpu_load_op_or_long.h",
   "$bindings_modules_v8_output_dir/gpu_sampler_or_gpu_texture_view_or_gpu_buffer_binding.cc",
   "$bindings_modules_v8_output_dir/gpu_sampler_or_gpu_texture_view_or_gpu_buffer_binding.h",
   "$bindings_modules_v8_output_dir/html_canvas_element_or_offscreen_canvas.cc",

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

@@ -289,9 +289,6 @@ DawnStoreOp AsDawnEnum<DawnStoreOp>(const WTF::String& webgpu_enum) {
 
 template <>
 DawnLoadOp AsDawnEnum<DawnLoadOp>(const WTF::String& webgpu_enum) {
-  if (webgpu_enum == "clear") {
-    return DAWN_LOAD_OP_CLEAR;
-  }
   if (webgpu_enum == "load") {
     return DAWN_LOAD_OP_LOAD;
   }

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

@@ -32,9 +32,22 @@ DawnRenderPassColorAttachmentDescriptor AsDawnType(
   dawn_desc.resolveTarget = webgpu_desc->resolveTarget()
                                 ? webgpu_desc->resolveTarget()->GetHandle()
                                 : nullptr;
-  dawn_desc.loadOp = AsDawnEnum<DawnLoadOp>(webgpu_desc->loadOp());
+
+  if (webgpu_desc->loadValue().IsGPULoadOp()) {
+    const WTF::String& gpuLoadOp = webgpu_desc->loadValue().GetAsGPULoadOp();
+    dawn_desc.loadOp = AsDawnEnum<DawnLoadOp>(gpuLoadOp);
+    dawn_desc.clearColor = AsDawnType(GPUColor::Create());
+
+  } else if (webgpu_desc->loadValue().IsGPUColor()) {
+    GPUColor* gpuColor = webgpu_desc->loadValue().GetAsGPUColor();
+    dawn_desc.loadOp = DAWN_LOAD_OP_CLEAR;
+    dawn_desc.clearColor = AsDawnType(gpuColor);
+
+  } else {
+    NOTREACHED();
+  }
+
   dawn_desc.storeOp = AsDawnEnum<DawnStoreOp>(webgpu_desc->storeOp());
-  dawn_desc.clearColor = AsDawnType(webgpu_desc->clearColor());
 
   return dawn_desc;
 }
@@ -47,14 +60,39 @@ DawnRenderPassDepthStencilAttachmentDescriptor AsDawnType(
 
   DawnRenderPassDepthStencilAttachmentDescriptor dawn_desc = {};
   dawn_desc.attachment = webgpu_desc->attachment()->GetHandle();
-  dawn_desc.depthLoadOp = AsDawnEnum<DawnLoadOp>(webgpu_desc->depthLoadOp());
+
+  if (webgpu_desc->depthLoadValue().IsGPULoadOp()) {
+    const WTF::String& gpuLoadOp =
+        webgpu_desc->depthLoadValue().GetAsGPULoadOp();
+    dawn_desc.depthLoadOp = AsDawnEnum<DawnLoadOp>(gpuLoadOp);
+    dawn_desc.clearDepth = 1.0f;
+
+  } else if (webgpu_desc->depthLoadValue().IsFloat()) {
+    dawn_desc.depthLoadOp = DAWN_LOAD_OP_CLEAR;
+    dawn_desc.clearDepth = webgpu_desc->depthLoadValue().GetAsFloat();
+
+  } else {
+    NOTREACHED();
+  }
+
   dawn_desc.depthStoreOp = AsDawnEnum<DawnStoreOp>(webgpu_desc->depthStoreOp());
-  dawn_desc.clearDepth = webgpu_desc->clearDepth();
-  dawn_desc.stencilLoadOp =
-      AsDawnEnum<DawnLoadOp>(webgpu_desc->stencilLoadOp());
+
+  if (webgpu_desc->stencilLoadValue().IsGPULoadOp()) {
+    const WTF::String& gpuLoadOp =
+        webgpu_desc->stencilLoadValue().GetAsGPULoadOp();
+    dawn_desc.stencilLoadOp = AsDawnEnum<DawnLoadOp>(gpuLoadOp);
+    dawn_desc.clearStencil = 0;
+
+  } else if (webgpu_desc->stencilLoadValue().IsLong()) {
+    dawn_desc.stencilLoadOp = DAWN_LOAD_OP_CLEAR;
+    dawn_desc.clearStencil = webgpu_desc->stencilLoadValue().GetAsLong();
+
+  } else {
+    NOTREACHED();
+  }
+
   dawn_desc.stencilStoreOp =
       AsDawnEnum<DawnStoreOp>(webgpu_desc->stencilStoreOp());
-  dawn_desc.clearStencil = webgpu_desc->clearStencil();
 
   return dawn_desc;
 }

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

@@ -8,7 +8,6 @@ dictionary GPURenderPassColorAttachmentDescriptor {
     required GPUTextureView attachment;
     GPUTextureView? resolveTarget = null;
 
-    required GPULoadOp loadOp;
+    required (GPULoadOp or GPUColor) loadValue;
     required GPUStoreOp storeOp;
-    required GPUColor clearColor;
 };

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

@@ -7,11 +7,9 @@
 dictionary GPURenderPassDepthStencilAttachmentDescriptor {
     required GPUTextureView attachment;
 
-    required GPULoadOp depthLoadOp;
+    required (GPULoadOp or float) depthLoadValue;
     required GPUStoreOp depthStoreOp;
-    required float clearDepth;
 
-    required GPULoadOp stencilLoadOp;
+    required (GPULoadOp or long) stencilLoadValue;
     required GPUStoreOp stencilStoreOp;
-    unsigned long clearStencil = 0;
 };

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

@@ -10,7 +10,6 @@ dictionary GPURenderPassDescriptor {
 };
 
 enum GPULoadOp {
-    "clear",
     "load"
 };