exo: Fix use of invalid texture mailbox.

components/exo/buffer.cc

Index: components/exo/buffer.cc
diff --git a/components/exo/buffer.cc b/components/exo/buffer.cc
index c5c35b1a4761b27402b5aae69864d15007d411e3..a799dccef8184a04d1b91ebaff510631c5306b37 100644
--- a/components/exo/buffer.cc
+++ b/components/exo/buffer.cc
@@ -464,9 +464,10 @@ bool Buffer::ProduceTransferableResource(
     Texture* texture = contents_texture_.get();
 
     // This binds the latest contents of this buffer to |texture|.
-    resource->mailbox_holder = gpu::MailboxHolder(
-        texture->mailbox(), texture->BindTexImage(), texture_target_);
+    gpu::SyncToken sync_token = texture->BindTexImage();
 
+    resource->mailbox_holder =
+        gpu::MailboxHolder(texture->mailbox(), sync_token, texture_target_);
     resource->is_overlay_candidate = is_overlay_candidate_;
 
     // The contents texture will be released when no longer used by the