--- a/gfx/webrender_bindings/Moz2DImageRenderer.cpp
+++ b/gfx/webrender_bindings/Moz2DImageRenderer.cpp
@@ -89,33 +89,33 @@ static struct FontDeleteLog {
       } else if (mEntries[offset] == namespaceEntry) {
         return "cleared namespace";
       }
     } while (offset != mNextEntry);
     return "unknown font";
   }
 } sFontDeleteLog;
 
+extern "C" {
 void
 ClearBlobImageResources(WrIdNamespace aNamespace) {
   StaticMutexAutoLock lock(sFontDataTableLock);
   sFontDeleteLog.Add(aNamespace);
   for (auto i = sFontDataTable.begin(); i != sFontDataTable.end();) {
     if (i->first.mNamespace == aNamespace) {
       if (i->second.mVec) {
         wr_dec_ref_arc(i->second.mVec);
       }
       i = sFontDataTable.erase(i);
     } else {
       i++;
     }
   }
 }
 
-extern "C" {
 void
 AddFontData(WrFontKey aKey, const uint8_t *aData, size_t aSize, uint32_t aIndex, const ArcVecU8 *aVec) {
   StaticMutexAutoLock lock(sFontDataTableLock);
   auto i = sFontDataTable.find(aKey);
   if (i == sFontDataTable.end()) {
     FontTemplate font;
     font.mData = aData;
     font.mSize = aSize;

--- a/gfx/webrender_bindings/WebRenderAPI.cpp
+++ b/gfx/webrender_bindings/WebRenderAPI.cpp
@@ -352,18 +352,16 @@ WebRenderAPI::CreateDocument(LayoutDevic
   return api.forget();
 }
 
 wr::WrIdNamespace
 WebRenderAPI::GetNamespace() {
   return wr_api_get_namespace(mDocHandle);
 }
 
-extern void ClearBlobImageResources(WrIdNamespace aNamespace);
-
 WebRenderAPI::~WebRenderAPI()
 {
   if (!mRootDocumentApi) {
     wr_api_delete_document(mDocHandle);
   }
 
   if (!mRootApi) {
     RenderThread::Get()->SetDestroyed(GetId());
@@ -371,31 +369,16 @@ WebRenderAPI::~WebRenderAPI()
     layers::SynchronousTask task("Destroy WebRenderAPI");
     auto event = MakeUnique<RemoveRenderer>(&task);
     RunOnRenderThread(Move(event));
     task.Wait();
 
     wr_api_shut_down(mDocHandle);
   }
 
-  // wr_api_get_namespace cannot be marked destructor-safe because it has a
-  // return value, and we can't call it if MOZ_BUILD_WEBRENDER is not defined
-  // because it's not destructor-safe. So let's just ifdef around it. This is
-  // basically a hack to get around compile-time warnings, this code never runs
-  // unless MOZ_BUILD_WEBRENDER is defined anyway.
-#ifdef MOZ_BUILD_WEBRENDER
-  wr::WrIdNamespace ns = GetNamespace();
-#else
-  wr::WrIdNamespace ns{0};
-#endif
-
-  // Clean up any resources the blob image renderer is holding onto that
-  // can no longer be used once this WR API instance goes away.
-  ClearBlobImageResources(ns);
-
   wr_api_delete(mDocHandle);
 }
 
 void
 WebRenderAPI::SendTransaction(TransactionBuilder& aTxn)
 {
   wr_transaction_update_resources(aTxn.Raw(), aTxn.RawUpdates());
   wr_api_send_transaction(mDocHandle, aTxn.Raw());

--- a/gfx/webrender_bindings/src/bindings.rs
+++ b/gfx/webrender_bindings/src/bindings.rs
@@ -58,17 +58,17 @@ impl WrExternalImageBufferType {
 /// cbindgen:field-names=[mHandle]
 /// cbindgen:derive-lt=true
 /// cbindgen:derive-lte=true
 type WrEpoch = Epoch;
 /// cbindgen:field-names=[mHandle]
 /// cbindgen:derive-lt=true
 /// cbindgen:derive-lte=true
 /// cbindgen:derive-neq=true
-type WrIdNamespace = IdNamespace;
+pub type WrIdNamespace = IdNamespace;
 
 /// cbindgen:field-names=[mNamespace, mHandle]
 type WrPipelineId = PipelineId;
 /// cbindgen:field-names=[mNamespace, mHandle]
 /// cbindgen:derive-neq=true
 type WrImageKey = ImageKey;
 /// cbindgen:field-names=[mNamespace, mHandle]
 pub type WrFontKey = FontKey;

--- a/gfx/webrender_bindings/src/moz2d_renderer.rs
+++ b/gfx/webrender_bindings/src/moz2d_renderer.rs
@@ -489,27 +489,29 @@ impl BlobImageRenderer for Moz2dImageRen
     }
     fn delete_font(&mut self, font: FontKey) {
         unsafe { DeleteFontData(font); }
     }
 
     fn delete_font_instance(&mut self, _key: FontInstanceKey) {
     }
 
-    fn clear_namespace(&mut self, _namespace: IdNamespace) {
+    fn clear_namespace(&mut self, namespace: IdNamespace) {
+        unsafe { ClearBlobImageResources(namespace); }
     }
 }
 
-use bindings::WrFontKey;
+use bindings::{WrFontKey, WrIdNamespace};
 
 #[allow(improper_ctypes)] // this is needed so that rustc doesn't complain about passing the &Arc<Vec> to an extern function
 extern "C" {
     fn AddFontData(key: WrFontKey, data: *const u8, size: usize, index: u32, vec: &ArcVecU8);
     fn AddNativeFontHandle(key: WrFontKey, handle: *mut c_void, index: u32);
     fn DeleteFontData(key: WrFontKey);
+    fn ClearBlobImageResources(namespace: WrIdNamespace);
 }
 
 impl Moz2dImageRenderer {
     pub fn new(workers: Arc<ThreadPool>) -> Self {
         let (tx, rx) = channel();
         Moz2dImageRenderer {
             blob_commands: HashMap::new(),
             rendered_images: HashMap::new(),