Revert of Remove SendPacer from ViEEncoder

webrtc/call/bitrate_allocator.h

Index: webrtc/call/bitrate_allocator.h
diff --git a/webrtc/call/bitrate_allocator.h b/webrtc/call/bitrate_allocator.h
index fc88b783b5e02e7f8b89e48a640ea04962f3ffb2..404a312dad3745d70c3b4c71af7150dc9f02eee7 100644
--- a/webrtc/call/bitrate_allocator.h
+++ b/webrtc/call/bitrate_allocator.h
@@ -60,6 +60,9 @@
 
   void RemoveObserver(BitrateAllocatorObserver* observer);
 
+  void GetMinMaxBitrateSumBps(int* min_bitrate_sum_bps,
+                              int* max_bitrate_sum_bps) const;
+
   // This method controls the behavior when the available bitrate is lower than
   // the minimum bitrate, or the sum of minimum bitrates.
   // When true, the bitrate will never be set lower than the minimum bitrate(s).
@@ -94,7 +97,6 @@
                                           uint32_t sum_min_bitrates)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
 
-  ObserverBitrateMap ZeroRateAllocation() EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
   ObserverBitrateMap LowRateAllocation(uint32_t bitrate)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);