Don't expire certs used as channel IDs.

net/ssl/server_bound_cert_service.h

Index: net/ssl/server_bound_cert_service.h
diff --git a/net/ssl/server_bound_cert_service.h b/net/ssl/server_bound_cert_service.h
index 734199e3471c0981fe9f5dda91cabaea5534276a..d95609a051bf4ef11d07d46ca22028fab6daaddf 100644
--- a/net/ssl/server_bound_cert_service.h
+++ b/net/ssl/server_bound_cert_service.h
@@ -29,7 +29,14 @@ class ServerBoundCertServiceJob;
 class ServerBoundCertServiceRequest;
 class ServerBoundCertServiceWorker;
 
-// A class for creating and fetching server bound certs.
+// A class for creating and fetching server bound certs. These certs are used
+// to identify users' machines; their public keys are used as channel IDs in
+// http://tools.ietf.org/html/draft-balfanz-tls-channelid-00.
+// As a result although certs are set to be invalid after one year, we don't
+// actually expire them. Once generated, certs are valid as long as the users
+// want. Users can delete existing certs, and new certs will be generated
+// automatically.
+
 // Inherits from NonThreadSafe in order to use the function
 // |CalledOnValidThread|.
 class NET_EXPORT ServerBoundCertService
@@ -79,12 +86,6 @@ class NET_EXPORT ServerBoundCertService
   // the origin otherwise.
   static std::string GetDomainForHost(const std::string& host);
 
-  // Tests whether the system time is within the supported range for
-  // certificate generation.  This value is cached when ServerBoundCertService
-  // is created, so if the system time is changed by a huge amount, this may no
-  // longer hold.
-  bool IsSystemTimeValid() const { return is_system_time_valid_; }
-
   // Fetches the domain bound cert for the specified origin of the specified
   // type if one exists and creates one otherwise. Returns OK if successful or
   // an error code upon failure.
@@ -155,8 +156,6 @@ class NET_EXPORT ServerBoundCertService
   uint64 cert_store_hits_;
   uint64 inflight_joins_;
 
-  bool is_system_time_valid_;
-
   DISALLOW_COPY_AND_ASSIGN(ServerBoundCertService);
 };