Change the unintentioal CHECK to DCHECK in DtlsIdentityStore.
Change the unintentioal CHECK to DCHECK in DtlsIdentityStore.

R=pthatcher@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/41139004

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#8636}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: b4cd093f41bb9de42fedae1767444bef1d178aac

dcpang/fatline-libjingle,sippet/talk,sippet/talk,sippet/talk,dcpang/fatline-libjingle,dcpang/fatline-libjingle,sippet/talk,dcpang/fatline-libjingle,dcpang/fatline-libjingle,sippet/talk