frame transformer: make GetPayloadType pure virtual again

after chrome was updated in
  https://chromium-review.googlesource.com/c/chromium/src/+/3103323

BUG=webrtc:13077

Change-Id: I7e5ff6aaae81c5dcfbaa41b09ef01bc95bb7251a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/230143
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Cr-Commit-Position: refs/heads/main@{#34877}
diff --git a/api/frame_transformer_interface.h b/api/frame_transformer_interface.h
index ca3a15a..7653bee 100644
--- a/api/frame_transformer_interface.h
+++ b/api/frame_transformer_interface.h
@@ -33,9 +33,7 @@
   // Copies `data` into the owned frame payload data.
   virtual void SetData(rtc::ArrayView<const uint8_t> data) = 0;
 
-  // TODO(bugs.webrtc.org/13077) make pure virtual again after rolling into
-  // Chrome.
-  virtual uint8_t GetPayloadType() const { return 255; }
+  virtual uint8_t GetPayloadType() const = 0;
   virtual uint32_t GetSsrc() const = 0;
   virtual uint32_t GetTimestamp() const = 0;
 };