To make it generally faster, specially in case of very large picture id gaps. Bug: None Change-Id: Ib0c49c17bd1281190da986def43bea8fc3440c0f Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/168055 Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Philip Eliasson <philipel@webrtc.org> Cr-Commit-Position: refs/heads/master@{#30438}