Request keyframe if too many packets are missing and NACK is disabled.

webrtc/modules/video_coding/main/source/jitter_buffer.h

Index: webrtc/modules/video_coding/main/source/jitter_buffer.h
diff --git a/webrtc/modules/video_coding/main/source/jitter_buffer.h b/webrtc/modules/video_coding/main/source/jitter_buffer.h
index 455ac2643cfcb90f25f5b4b9a991549b4c24d8af..5ae7c4b8d6651204a9bed87551a5bb6b174767ce 100644
--- a/webrtc/modules/video_coding/main/source/jitter_buffer.h
+++ b/webrtc/modules/video_coding/main/source/jitter_buffer.h
@@ -226,10 +226,12 @@ class VCMJitterBuffer {
   void FindAndInsertContinuousFrames(const VCMFrameBuffer& new_frame)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
   VCMFrameBuffer* NextFrame() const EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
-  // Returns true if the NACK list was updated to cover sequence numbers up to
-  // |sequence_number|. If false a key frame is needed to get into a state where
-  // we can continue decoding.
-  bool UpdateNackList(uint16_t sequence_number)
+  // Returns true if sequence numbers are covered up to |sequence_number|. The
+  // NACK list will be used to handle missing packets if enabled.
+  // Returns false if a key frame is needed to get into a state where we can
+  // continue decoding. Without NACK this is always the case if packets are
+  // missing.
+  bool CoverSequenceUpTo(uint16_t sequence_number)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
   bool TooLargeNackList() const;
   // Returns true if the NACK list was reduced without problem. If false a key