message: Remove deprecated constant.
  Cr-Commit-Position: refs/heads/master@{#31137}
diff: @@ -30,8 +30,6 @@ struct CallConfig {
  CallConfig(const CallConfig&);
  ~CallConfig();
  - RTC_DEPRECATED static constexpr int kDefaultStartBitrateBps = 300000;
  -
  // Bitrate config used until valid bitrate estimates are calculated. Also
  // used to cap total bitrate used. This comes from the remote connection.
  BitrateConstraints bitrate_config;
  