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

net/cert/internal/system_trust_store.h

Index: net/cert/internal/system_trust_store.h
diff --git a/net/cert/internal/system_trust_store.h b/net/cert/internal/system_trust_store.h
index 2783ce2a710f9e4e37173f2c048551bce5e7c94d..028ff8c3c09512a6718651928679eca65c12dd73 100644
--- a/net/cert/internal/system_trust_store.h
+++ b/net/cert/internal/system_trust_store.h
@@ -14,7 +14,6 @@
 namespace net {
 
 class TrustStore;
-class CertIssuerSource;
 class TrustAnchor;
 
 // The SystemTrustStore interface is used to encapsulate a TrustStore for the
@@ -46,15 +45,6 @@ class SystemTrustStore {
   // trust anchors (via AddTrustAnchor()).
   virtual bool UsesSystemTrustStore() const = 0;
 
-  // TODO(eroman): Expose this through the TrustStore interface instead?
-  //
-  // Returns a CertIssuerSource that finds any intermediates that are present in
-  // the system trust store. These intermediates are not necessarily trusted,
-  // however may be used during path building as another means of finding
-  // certificates. If the implementation of SystemTrustStore doesn't support
-  // this feature may return nullptr.
-  virtual CertIssuerSource* GetCertIssuerSource() = 0;
-
   // IsKnownRoot() returns true if the given trust anchor originated from the
   // system trust store and is a "standard" one. The meaning of "standard" is
   // that it is one of default trust anchors for the system, as opposed to a