Increase packet limit in jitter buffer.

Especially the VP9 codec currently may overshoot bitrate target at sudden picture changes, resulting in frames over 800 packets.
This limit should be reduced again once the codec behaves.

BUG=webrtc:4889

Review URL: https://codereview.webrtc.org/1266353003

Cr-Commit-Position: refs/heads/master@{#9675}

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

@@ -28,7 +28,9 @@ enum { kFastConvergeThreshold = 5};
 enum VCMJitterBufferEnum {
   kMaxConsecutiveOldFrames = 60,
   kMaxConsecutiveOldPackets = 300,
-  kMaxPacketsInSession            = 800,
+  // TODO(sprang): Reduce this limit once codecs don't sometimes wildly
+  // overshoot bitrate target.
+  kMaxPacketsInSession = 1400,      // Allows ~2MB frames.
   kBufferIncStepSizeBytes = 30000,  // >20 packets.
   kMaxJBFrameSizeBytes = 4000000    // sanity don't go above 4Mbyte.
 };