Follow-up changes to https://codereview.chromium.org/795773002/

content/public/browser/content_browser_client.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_PUBLIC_BROWSER_CONTENT_BROWSER_CLIENT_H_
 #define CONTENT_PUBLIC_BROWSER_CONTENT_BROWSER_CLIENT_H_
 
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 377 matching lines @@
                                      const net::SSLInfo& ssl_info,
                                      const GURL& request_url,
                                      ResourceType resource_type,
                                      bool overridable,
                                      bool strict_enforcement,
                                      bool expired_previous_decision,
                                      const base::Callback<void(bool)>& callback,
                                      CertificateRequestResultType* result) {}
 
   // Selects a SSL client certificate and returns it to the |callback|. If no
-  // certificate was selected nullptr is returned to the |callback|.
+  // certificate was selected nullptr is returned to the |callback|. Note:
+  // |callback| may be called synchronously or asynchronously.
   virtual void SelectClientCertificate(
       int render_process_id,
       int render_frame_id,
       net::SSLCertRequestInfo* cert_request_info,
       const base::Callback<void(net::X509Certificate*)>& callback);
 
   // Adds a new installable certificate or private key.
   // Typically used to install an X.509 user certificate.
   // Note that it's up to the embedder to verify that the data is
   // well-formed. |cert_data| will be nullptr if |cert_size| is 0.
@@ skipping 203 matching lines @@
   // Allows an embedder to provide its own ExternalVideoSurfaceContainer
   // implementation.  Return nullptr to disable external surface video.
   virtual ExternalVideoSurfaceContainer*
   OverrideCreateExternalVideoSurfaceContainer(WebContents* web_contents);
 #endif
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_CONTENT_BROWSER_CLIENT_H_