Delete EncodedImage::GetBufferPaddingBytes

For the ffmpeg H.264 decoder, rely on ffmpeg being configured with
CONFIG_SAFE_BITSTREAM_READER.

Bug: webrtc:9378
Change-Id: Ia7a46580d520808e36581252a95feeb5f9c57bf9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/119665
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27124}
diff --git a/modules/video_coding/frame_buffer.cc b/modules/video_coding/frame_buffer.cc
index a4c92ad..19b822b 100644
--- a/modules/video_coding/frame_buffer.cc
+++ b/modules/video_coding/frame_buffer.cc
@@ -102,8 +102,7 @@
 
   uint32_t requiredSizeBytes =
       size() + packet.sizeBytes +
-      (packet.insertStartCode ? kH264StartCodeLengthBytes : 0) +
-      EncodedImage::GetBufferPaddingBytes(packet.codec());
+      (packet.insertStartCode ? kH264StartCodeLengthBytes : 0);
   if (requiredSizeBytes >= capacity()) {
     const uint8_t* prevBuffer = data();
     const uint32_t increments =