message: frame transformer: make GetPayloadType pure virtual again
  after chrome was updated in
  Cr-Commit-Position: refs/heads/main@{#34877}
diff: @@ -33,9 +33,7 @@ class TransformableFrameInterface {
  // 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;
  };
  