Implement ChannelIDVerifier using NSS.

net/quic/crypto/channel_id.h

Index: net/quic/crypto/channel_id.h
===================================================================
--- net/quic/crypto/channel_id.h	(revision 203993)
+++ net/quic/crypto/channel_id.h	(working copy)
@@ -44,6 +44,15 @@
   static bool Verify(base::StringPiece key,
                      base::StringPiece signed_data,
                      base::StringPiece signature);
+
+  // FOR TESTING ONLY: VerifyRaw returns true iff |signature| is a valid
+  // signature of |signed_data| by |key|. |is_channel_id_signature| indicates
+  // whether |signature| is a ChannelID signature (with kContextStr prepended
+  // to the data to be signed).
+  static bool VerifyRaw(base::StringPiece key,
+                        base::StringPiece signed_data,
+                        base::StringPiece signature,
+                        bool is_channel_id_signature);
 };
 
 }  // namespace net