dawn_native: Add RequestDevice to the Adapter

Adds a basic RequestDevice method to the adapter, only in
dawn_native. We will revisit this when we implement adapters
in dawn_wire.

RequestDevice allows us to have tests of the limit bounds
because it receives a callback which can return status codes
and error messages.

Bug: dawn:685
Change-Id: I7a68922b078c6a436f49a16346cb41fb9df9cfee
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/63982
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

src/dawn_native/Adapter.cpp

@@ -78,6 +78,24 @@ namespace dawn_native {
         return result;
     }
 
+    void AdapterBase::RequestDevice(const DeviceDescriptor* descriptor,
+                                    WGPURequestDeviceCallback callback,
+                                    void* userdata) {
+        DeviceBase* result = nullptr;
+        MaybeError err = CreateDeviceInternal(&result, descriptor);
+        WGPUDevice device = reinterpret_cast<WGPUDevice>(result);
+
+        if (err.IsError()) {
+            std::unique_ptr<ErrorData> errorData = err.AcquireError();
+            callback(WGPURequestDeviceStatus_Error, device, errorData->GetMessage().c_str(),
+                     userdata);
+            return;
+        }
+        WGPURequestDeviceStatus status =
+            device == nullptr ? WGPURequestDeviceStatus_Unknown : WGPURequestDeviceStatus_Success;
+        callback(status, device, nullptr, userdata);
+    }
+
     MaybeError AdapterBase::CreateDeviceInternal(DeviceBase** result,
                                                  const DeviceDescriptor* descriptor) {
         if (descriptor != nullptr) {

src/dawn_native/Adapter.h

@@ -40,6 +40,10 @@ namespace dawn_native {
 
         DeviceBase* CreateDevice(const DeviceDescriptor* descriptor = nullptr);
 
+        void RequestDevice(const DeviceDescriptor* descriptor,
+                           WGPURequestDeviceCallback callback,
+                           void* userdata);
+
         void ResetInternalDeviceForTesting();
 
         ExtensionsSet GetSupportedExtensions() const;

src/dawn_native/DawnNative.cpp

@@ -118,6 +118,12 @@ namespace dawn_native {
         return reinterpret_cast<WGPUDevice>(mImpl->CreateDevice(deviceDescriptor));
     }
 
+    void Adapter::RequestDevice(const DeviceDescriptor* descriptor,
+                                WGPURequestDeviceCallback callback,
+                                void* userdata) {
+        mImpl->RequestDevice(descriptor, callback, userdata);
+    }
+
     void Adapter::ResetInternalDeviceForTesting() {
         mImpl->ResetInternalDeviceForTesting();
     }

src/include/dawn_native/DawnNative.h

@@ -120,6 +120,10 @@ namespace dawn_native {
         // On an error, nullptr is returned.
         WGPUDevice CreateDevice(const DeviceDescriptor* deviceDescriptor = nullptr);
 
+        void RequestDevice(const DeviceDescriptor* descriptor,
+                           WGPURequestDeviceCallback callback,
+                           void* userdata);
+
         // Reset the backend device object for testing purposes.
         void ResetInternalDeviceForTesting();