Refactor rate profile update.

RateProfile::frame_num specifies frame at which this rate profile
should be applied.

Bug: none
Change-Id: I003ee43f44299a49d83f547558284817bfaeacc0
Reviewed-on: https://webrtc-review.googlesource.com/c/115242
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Seth Hampson <shampson@webrtc.org>
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26080}

modules/video_coding/codecs/test/videocodec_test_parameterized.cc

@@ -67,8 +67,7 @@ class VideoCodecTestParameterized
                             kDenoisingOn, kFrameDropperOn, kSpatialResizeOn,
                             width, height);
 
-    std::vector<RateProfile> rate_profiles = {
-        {bitrate_, framerate, kNumFrames}};
+    std::vector<RateProfile> rate_profiles = {{bitrate_, framerate, 0}};
 
     fixture_ = CreateVideoCodecTestFixture(config);
     fixture_->RunTest(rate_profiles, nullptr, nullptr, nullptr);