Bug 1955057 - feat(webgpu): add GPUAdapterInfo.isFallbackAdapter r=webgpu-reviewers,webidl,smaug,teoxoy

Differential Revision: https://phabricator.services.mozilla.com/D242390

dom/webgpu/Adapter.cpp

@@ -21,6 +21,18 @@ namespace mozilla::webgpu {
 GPU_IMPL_CYCLE_COLLECTION(AdapterInfo, mParent)
 GPU_IMPL_JS_WRAP(AdapterInfo)
 
+bool AdapterInfo::IsFallbackAdapter() const {
+  if (GetParentObject()->ShouldResistFingerprinting(
+          RFPTarget::WebGPUIsFallbackAdapter)) {
+    // Always report hardware support for WebGPU.
+    // This behaviour matches with media capabilities API.
+    return false;
+  }
+
+  return mAboutSupportInfo->device_type ==
+         ffi::WGPUDeviceType::WGPUDeviceType_Cpu;
+}
+
 void AdapterInfo::GetWgpuName(nsString& s) const {
   s = mAboutSupportInfo->name;
 }

dom/webgpu/Adapter.h

@@ -63,6 +63,7 @@ class AdapterInfo final : public nsWrapperCache, public ChildOf<Adapter> {
   void GetArchitecture(nsString& s) const { s = nsString(); }
   void GetDevice(nsString& s) const { s = nsString(); }
   void GetDescription(nsString& s) const { s = nsString(); }
+  bool IsFallbackAdapter() const;
 
   // Non-standard field getters; see also TODO BUGZILLA LINK
   void GetWgpuName(nsString&) const;

dom/webidl/WebGPU.webidl

@@ -70,6 +70,7 @@ interface GPUAdapterInfo {
     readonly attribute DOMString architecture;
     readonly attribute DOMString device;
     readonly attribute DOMString description;
+    readonly attribute boolean isFallbackAdapter;
 
     // Non-standard; see <https://bugzilla.mozilla.org/show_bug.cgi?id=1831994>.
     [ChromeOnly] readonly attribute DOMString wgpuName;