Delete KeepBufferRefs helpers, and use of rtc::Bind.

The rtc::Bind usages are replaced with lambdas with copy-capture
of the ref pointers.

Bug: webrtc:11339
Change-Id: I2fb544fcd2780feac3d725993c360df91899b532
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/201201
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32946}

modules/video_coding/codecs/multiplex/multiplex_decoder_adapter.cc

@@ -20,11 +20,6 @@
 #include "rtc_base/keep_ref_until_done.h"
 #include "rtc_base/logging.h"
 
-namespace {
-void KeepBufferRefs(rtc::scoped_refptr<webrtc::VideoFrameBuffer>,
-                    rtc::scoped_refptr<webrtc::VideoFrameBuffer>) {}
-}  // anonymous namespace
-
 namespace webrtc {
 
 class MultiplexDecoderAdapter::AdapterDecodedImageCallback
@@ -250,7 +245,8 @@ void MultiplexDecoderAdapter::MergeAlphaImages(
         yuv_buffer->StrideY(), yuv_buffer->DataU(), yuv_buffer->StrideU(),
         yuv_buffer->DataV(), yuv_buffer->StrideV(), alpha_buffer->DataY(),
         alpha_buffer->StrideY(),
-        rtc::Bind(&KeepBufferRefs, yuv_buffer, alpha_buffer));
+        // To keep references alive.
+        [yuv_buffer, alpha_buffer] {});
   }
   if (supports_augmenting_data_) {
     merged_buffer = rtc::scoped_refptr<webrtc::AugmentedVideoFrameBuffer>(