Validate that the device is alive when creating an ExternalTexture

Fixed: dawn:1419
Change-Id: If536978889b9c2b41e63f0035183da4c2f8fe379
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/91160
Commit-Queue: Austin Eng <enga@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Auto-Submit: Corentin Wallez <cwallez@chromium.org>

src/dawn/native/Device.cpp

@@ -1555,6 +1555,7 @@ ResultOrError<Ref<PipelineLayoutBase>> DeviceBase::CreatePipelineLayout(
 
 ResultOrError<Ref<ExternalTextureBase>> DeviceBase::CreateExternalTextureImpl(
     const ExternalTextureDescriptor* descriptor) {
+    DAWN_TRY(ValidateIsAlive());
     if (IsValidationEnabled()) {
         DAWN_TRY_CONTEXT(ValidateExternalTextureDescriptor(this, descriptor), "validating %s",
                          descriptor);