Remove unused dawn::native::metal::GetMetalDevice

Bug: None
Change-Id: I07d4c2f4afce9202619e9def9dd1a214ae0906a4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/97203
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
diff --git a/include/dawn/native/MetalBackend.h b/include/dawn/native/MetalBackend.h
index 20c8048..72a9cb0 100644
--- a/include/dawn/native/MetalBackend.h
+++ b/include/dawn/native/MetalBackend.h
@@ -60,14 +60,6 @@
 
 }  // namespace dawn::native::metal
 
-#ifdef __OBJC__
-namespace dawn::native::metal {
-
-DAWN_NATIVE_EXPORT id<MTLDevice> GetMetalDevice(WGPUDevice device);
-
-}  // namespace dawn::native::metal
-#endif  // __OBJC__
-
 #pragma clang diagnostic pop
 
 #endif  // INCLUDE_DAWN_NATIVE_METALBACKEND_H_
diff --git a/src/dawn/native/metal/MetalBackend.mm b/src/dawn/native/metal/MetalBackend.mm
index f6cbbdc..d414020 100644
--- a/src/dawn/native/metal/MetalBackend.mm
+++ b/src/dawn/native/metal/MetalBackend.mm
@@ -22,10 +22,6 @@
 
 namespace dawn::native::metal {
 
-id<MTLDevice> GetMetalDevice(WGPUDevice device) {
-    return ToBackend(FromAPI(device))->GetMTLDevice();
-}
-
 AdapterDiscoveryOptions::AdapterDiscoveryOptions()
     : AdapterDiscoveryOptionsBase(WGPUBackendType_Metal) {}