Allow the TrustStore interface to return matching intermediates, and identify distrusted certs.

net/cert/internal/system_trust_store.cc

Index: net/cert/internal/system_trust_store.cc
diff --git a/net/cert/internal/system_trust_store.cc b/net/cert/internal/system_trust_store.cc
index 64ac20982abdf24a1c9a1b47143a4f6f368e4c1a..b836e465553e12ecabe11ff534fdfb5e6b906d6d 100644
--- a/net/cert/internal/system_trust_store.cc
+++ b/net/cert/internal/system_trust_store.cc
@@ -17,7 +17,6 @@
 
 #if defined(USE_NSS_CERTS)
 #include "crypto/nss_util.h"
-#include "net/cert/internal/cert_issuer_source_nss.h"
 #include "net/cert/internal/trust_store_nss.h"
 #include "net/cert/scoped_nss_types.h"
 #elif defined(OS_MACOSX) && !defined(OS_IOS)
@@ -42,8 +41,6 @@ class BaseSystemTrustStore : public SystemTrustStore {
 
   TrustStore* GetTrustStore() override { return &trust_store_; }
 
-  CertIssuerSource* GetCertIssuerSource() override { return nullptr; }
-
   bool IsAdditionalTrustAnchor(
       const scoped_refptr<TrustAnchor>& trust_anchor) const override {
     return additional_trust_store_.Contains(trust_anchor.get());
@@ -65,10 +62,6 @@ class SystemTrustStoreNSS : public BaseSystemTrustStore {
     trust_store_.AddTrustStore(&trust_store_nss_);
   }
 
-  CertIssuerSource* GetCertIssuerSource() override {
-    return &cert_issuer_source_nss_;
-  }
-
   bool UsesSystemTrustStore() const override { return true; }
 
   // IsKnownRoot returns true if the given trust anchor is a standard one (as
@@ -112,7 +105,6 @@ class SystemTrustStoreNSS : public BaseSystemTrustStore {
   }
 
   TrustStoreNSS trust_store_nss_;
-  CertIssuerSourceNSS cert_issuer_source_nss_;
 };
 
 }  // namespace
@@ -129,11 +121,6 @@ class SystemTrustStoreMac : public BaseSystemTrustStore {
     trust_store_.AddTrustStore(&trust_store_mac_);
   }
 
-  CertIssuerSource* GetCertIssuerSource() override {
-    // TODO(eroman): Should this return something?
-    return nullptr;
-  }
-
   bool UsesSystemTrustStore() const override { return true; }
 
   // IsKnownRoot returns true if the given trust anchor is a standard one (as