Improvements for NetEqControllers

When creating a NetEqController it can be useful to have access to a
webrtc::Clock*. Also, NetEqControllers should have access to the
contents of the sync buffer when making decisions.

Bug: webrtc:11005
Change-Id: I7fdba75ce661b2ace52458620a8c1f3c990e5ac2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/167208
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30368}

modules/audio_coding/neteq/neteq_impl_unittest.cc

@@ -125,6 +125,7 @@ class NetEqImplTest : public ::testing::Test {
       controller_config.enable_rtx_handling = config_.enable_rtx_handling;
       controller_config.allow_time_stretching = true;
       controller_config.max_packets_in_buffer = config_.max_packets_in_buffer;
+      controller_config.clock = &clock_;
       deps.neteq_controller =
           std::make_unique<DecisionLogic>(std::move(controller_config));
     }