Add a defaulted ExternalTextureBase destructor.

Without this, users of ExternalTextureBase will try to instantiate the
default destructor, which will cause a call to ~Ref<BufferBase> which
will fail when Buffer.h isn't included.

Fixes the roll of Dawn in google3.

Bug: None
Change-Id: Ib88d4338033468779f416973e5808910eb4ef110
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/78721
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Auto-Submit: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/dawn_native/ExternalTexture.cpp

@@ -119,6 +119,8 @@ namespace dawn::native {
         : ApiObjectBase(device, tag) {
     }
 
+    ExternalTextureBase::~ExternalTextureBase() = default;
+
     MaybeError ExternalTextureBase::Initialize(DeviceBase* device,
                                                const ExternalTextureDescriptor* descriptor) {
         // Store any passed in TextureViews associated with individual planes.

src/dawn_native/ExternalTexture.h

@@ -58,6 +58,8 @@ namespace dawn::native {
         ExternalTextureBase(DeviceBase* device);
         void DestroyImpl() override;
 
+        ~ExternalTextureBase() override;
+
       private:
         enum class ExternalTextureState { Alive, Destroyed };
         ExternalTextureBase(DeviceBase* device, const ExternalTextureDescriptor* descriptor);