Remove DCHECK from common_types.cc
Remove DCHECK from common_types.cc

The DCHECKs added in https://webrtc-codereview.appspot.com/41069004/
introduces a dependency on base, which may cause problems.
This CL reverts that change.

R=tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/48389004

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#8602}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 7b93ea1667a726d9716508389f9472bb61396299

jchavanton/webrtc,sippet/webrtc,krieger-od/webrtc,Alkalyne/webrtctrunk,jchavanton/webrtc,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,aleonliao/webrtc-trunk,krieger-od/webrtc,jchavanton/webrtc,krieger-od/webrtc,sippet/webrtc,aleonliao/webrtc-trunk,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,jchavanton/webrtc,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,krieger-od/webrtc,sippet/webrtc,Alkalyne/webrtctrunk,aleonliao/webrtc-trunk,sippet/webrtc,sippet/webrtc,jchavanton/webrtc,Alkalyne/webrtctrunk,krieger-od/webrtc,jchavanton/webrtc,sippet/webrtc,jchavanton/webrtc,krieger-od/webrtc