Handle certificate generation errors in chromoting host.

remoting/host/host_key_pair.h

Index: remoting/host/host_key_pair.h
diff --git a/remoting/host/host_key_pair.h b/remoting/host/host_key_pair.h
index 8af41d931532f0305a94300fe7c7af25c6fe2d28..f7aa651a8d3d3f1db33e375fcb8ecfb957342ad3 100644
--- a/remoting/host/host_key_pair.h
+++ b/remoting/host/host_key_pair.h
@@ -37,6 +37,9 @@ class HostKeyPair {
 
   // Make a new copy of private key. Caller will own the generated private key.
   crypto::RSAPrivateKey* CopyPrivateKey() const;
+
+  // Generates self-signed certificate using the key pair. Returns empty string
+  // if cert generation fails (e.g. it may happen when the system clock is off).
   std::string GenerateCertificate() const;
 
  private: