Remove SendPacer from ViEEncoder and make sure SendPacer starts at a valid bitrate

This reverts commit e30c27205148b34ba421184efe65f6a0780b436d (https://codereview.webrtc.org/1958053002/)

Original reverted cl is in patch set #1.
Changes in following patch sets.

The cl now also make sure SendPacer starts with the configured bitrate provided in a call to CongestionController::SetBweBitrates)()

It turns out that the failing tests in 609816 is due to a bug in the current code that runs the proper at 300kbit regardless of configured start bitrate.

Original cl description:
Remove SendPacer from ViEEncoder
This CL moves the logic where the ViEEncoder pause if the pacer is full to the BitrateController. If the queue is full, the controller reports a bitrate of zero to  Call (and BitrateAllocator)

BUG=chromium:609816, webrtc:5687
TBR=mflodman@webrtc.org
NOTRY=True  // Due to bug  in android_x86 cq builder....

Review-Url: https://codereview.webrtc.org/1958113003
Cr-Commit-Position: refs/heads/master@{#12688}

webrtc/call/call.cc

diff --git a/webrtc/call/call.cc b/webrtc/call/call.cc
index 82ca630..f7c66db 100644
--- a/webrtc/call/call.cc
+++ b/webrtc/call/call.cc
@@ -52,8 +52,9 @@
 
 namespace internal {
 
-class Call : public webrtc::Call, public PacketReceiver,
-             public BitrateObserver {
+class Call : public webrtc::Call,
+             public PacketReceiver,
+             public CongestionController::Observer {
  public:
   explicit Call(const Call::Config& config);
   virtual ~Call();
@@ -699,10 +700,8 @@
     pacer_bitrate_sum_kbits_ += pacer_bitrate_bps / 1000;
     ++num_bitrate_updates_;
   }
-  congestion_controller_->UpdatePacerBitrate(
-      target_bitrate_bps / 1000,
-      PacedSender::kDefaultPaceMultiplier * pacer_bitrate_bps / 1000,
-      pad_up_to_bitrate_bps / 1000);
+  congestion_controller_->SetAllocatedSendBitrate(allocated_bitrate_bps,
+                                                  pad_up_to_bitrate_bps);
 }
 
 void Call::ConfigureSync(const std::string& sync_group) {