Rename EncoderKeyFrameCallback back to EncoderRtcpFeedback

The name EncoderRtcpFeedback is more appropriate because:
1. "Callback" implies a single function exposed, which is
   not the case.
2. We intend to add OnLossNotification() to the same class.

Bug: webrtc:10501
Change-Id: I75b2e06eb070e85e872eba9fbc354aa4b68c7993
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/131289
Commit-Queue: Elad Alon <eladalon@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27490}
diff --git a/video/BUILD.gn b/video/BUILD.gn
index 51dcb9d..b4b943c 100644
--- a/video/BUILD.gn
+++ b/video/BUILD.gn
@@ -14,8 +14,8 @@
     "buffered_frame_decryptor.h",
     "call_stats.cc",
     "call_stats.h",
-    "encoder_key_frame_callback.cc",
-    "encoder_key_frame_callback.h",
+    "encoder_rtcp_feedback.cc",
+    "encoder_rtcp_feedback.h",
     "quality_threshold.cc",
     "quality_threshold.h",
     "receive_statistics_proxy.cc",
@@ -465,8 +465,8 @@
       "call_stats_unittest.cc",
       "cpu_scaling_tests.cc",
       "encoder_bitrate_adjuster_unittest.cc",
-      "encoder_key_frame_callback_unittest.cc",
       "encoder_overshoot_detector_unittest.cc",
+      "encoder_rtcp_feedback_unittest.cc",
       "end_to_end_tests/bandwidth_tests.cc",
       "end_to_end_tests/call_operation_tests.cc",
       "end_to_end_tests/codec_tests.cc",