Provide method for returning certificate expiration timestamp.

webrtc/base/sslidentity.h

Index: webrtc/base/sslidentity.h
diff --git a/webrtc/base/sslidentity.h b/webrtc/base/sslidentity.h
index cf9942637e480de935bdfaad3667f18555ddccc2..94e9d03caf7fdcaf49c744b8beed8725fd4f7a11 100644
--- a/webrtc/base/sslidentity.h
+++ b/webrtc/base/sslidentity.h
@@ -68,6 +68,9 @@ class SSLCertificate {
                              unsigned char* digest,
                              size_t size,
                              size_t* length) const = 0;
+
+  // Returns the time in milliseconds relative to epoch.

[hbos, 2015/11/25 15:21:45]

Is it unambiguous what "epoch" means? Could you write out the datetime and zone
in the comment?

[torbjorng (webrtc), 2015/11/25 19:14:09]

https://en.wikipedia.org/wiki/Unix_time

+  virtual int64_t CertificateExpirationTime() const = 0;
 };
 
 // SSLCertChain is a simple wrapper for a vector of SSLCertificates. It serves
@@ -168,8 +171,8 @@ KeyType IntKeyTypeFamilyToKeyType(int key_type_family);
 // random string will be used.
 struct SSLIdentityParams {
   std::string common_name;
-  int not_before;  // offset from current time in seconds.
-  int not_after;   // offset from current time in seconds.
+  int not_before;      // Absolute time since epoch in seconds.
+  int not_after;       // Absolute time since epoch in seconds.

[hbos, 2015/11/25 15:21:45]

What happens at the wrap-around date (code using this)?

[torbjorng (webrtc), 2015/11/25 19:14:09]

I'll change this to time_t, which is more kosher (but still has problems after
2038 on older systems).

   KeyParams key_params;
 };