Implement GetChain for OpenSSLCertificate.

webrtc/rtc_base/opensslidentity.h

Index: webrtc/rtc_base/opensslidentity.h
diff --git a/webrtc/rtc_base/opensslidentity.h b/webrtc/rtc_base/opensslidentity.h
index ed7c07299a40fef713c6bff8e0bb0fed1e082a4c..fbbc0667493f1c47c4e3468e8d7cd569a9a33265 100644
--- a/webrtc/rtc_base/opensslidentity.h
+++ b/webrtc/rtc_base/opensslidentity.h
@@ -62,9 +62,10 @@ class OpenSSLKeyPair {
 class OpenSSLCertificate : public SSLCertificate {
  public:
   // Caller retains ownership of the X509 object.
-  explicit OpenSSLCertificate(X509* x509) : x509_(x509) {
-    AddReference();
-  }
+  explicit OpenSSLCertificate(X509* x509);
+
+  // Caller retains owership of STACK_OF(X509).
+  explicit OpenSSLCertificate(STACK_OF(X509)* chain);
 
   static OpenSSLCertificate* Generate(OpenSSLKeyPair* key_pair,
                                       const SSLIdentityParams& params);
@@ -100,9 +101,11 @@ class OpenSSLCertificate : public SSLCertificate {
   int64_t CertificateExpirationTime() const override;
 
  private:
-  void AddReference() const;
+  void AddReference(X509* x509) const;
 
   X509* x509_;
+  // Non-leaf certificate chain.
+  std::vector<OpenSSLCertificate*> cert_chain_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(OpenSSLCertificate);
 };