LibvpxVp9Encoder: add option to configure resolution_bitrate_limits.

Bug: none
Change-Id: Icdd7333296d652b1e0c159226df702084303475c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/204701
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Commit-Queue: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33121}

rtc_base/experiments/encoder_info_settings.h

@@ -57,6 +57,13 @@ class SimulcastEncoderAdapterEncoderInfoSettings : public EncoderInfoSettings {
   ~SimulcastEncoderAdapterEncoderInfoSettings() override {}
 };
 
+// EncoderInfo settings for LibvpxVp9Encoder.
+class LibvpxVp9EncoderInfoSettings : public EncoderInfoSettings {
+ public:
+  LibvpxVp9EncoderInfoSettings();
+  ~LibvpxVp9EncoderInfoSettings() override {}
+};
+
 }  // namespace webrtc
 
 #endif  // RTC_BASE_EXPERIMENTS_ENCODER_INFO_SETTINGS_H_