Remove the enable-net-security-expiration option (see issue #2622)

The implementation of this option was removed in commit 67b61c4. Certificate
transparency is disabled by default for Chromium embedders. Details at:

https://chromium.googlesource.com/chromium/src/+/master/net/docs/certificate-transparency.md#Supporting-Certificate-Transparency-for-Embedders

include/internal/cef_types.h

@@ -385,19 +385,6 @@ typedef struct _cef_settings_t {
   ///
   int ignore_certificate_errors;
 
-  ///
-  // Set to true (1) to enable date-based expiration of built in network
-  // security information (i.e. certificate transparency logs, HSTS preloading
-  // and pinning information). Enabling this option improves network security
-  // but may cause HTTPS load failures when using CEF binaries built more than
-  // 10 weeks in the past. See https://www.certificate-transparency.org/ and
-  // https://www.chromium.org/hsts for details. Also configurable using the
-  // "enable-net-security-expiration" command-line switch. Can be overridden for
-  // individual CefRequestContext instances via the
-  // CefRequestContextSettings.enable_net_security_expiration value.
-  ///
-  int enable_net_security_expiration;
-
   ///
   // Background color used for the browser before a document is loaded and when
   // no document color is specified. The alpha component must be either fully
@@ -479,17 +466,6 @@ typedef struct _cef_request_context_settings_t {
   ///
   int ignore_certificate_errors;
 
-  ///
-  // Set to true (1) to enable date-based expiration of built in network
-  // security information (i.e. certificate transparency logs, HSTS preloading
-  // and pinning information). Enabling this option improves network security
-  // but may cause HTTPS load failures when using CEF binaries built more than
-  // 10 weeks in the past. See https://www.certificate-transparency.org/ and
-  // https://www.chromium.org/hsts for details. Can be set globally using the
-  // CefSettings.enable_net_security_expiration value.
-  ///
-  int enable_net_security_expiration;
-
   ///
   // Comma delimited ordered list of language codes without any whitespace that
   // will be used in the "Accept-Language" HTTP header. Can be set globally

include/internal/cef_types_wrappers.h

@@ -603,8 +603,6 @@ struct CefSettingsTraits {
     target->remote_debugging_port = src->remote_debugging_port;
     target->uncaught_exception_stack_size = src->uncaught_exception_stack_size;
     target->ignore_certificate_errors = src->ignore_certificate_errors;
-    target->enable_net_security_expiration =
-        src->enable_net_security_expiration;
     target->background_color = src->background_color;
 
     cef_string_set(src->accept_language_list.str,
@@ -639,8 +637,6 @@ struct CefRequestContextSettingsTraits {
     target->persist_session_cookies = src->persist_session_cookies;
     target->persist_user_preferences = src->persist_user_preferences;
     target->ignore_certificate_errors = src->ignore_certificate_errors;
-    target->enable_net_security_expiration =
-        src->enable_net_security_expiration;
     cef_string_set(src->accept_language_list.str,
                    src->accept_language_list.length,
                    &target->accept_language_list, copy);

libcef/browser/context.cc

@@ -533,9 +533,6 @@ void CefContext::PopulateRequestContextSettings(
   settings->ignore_certificate_errors =
       settings_.ignore_certificate_errors ||
       command_line->HasSwitch(switches::kIgnoreCertificateErrors);
-  settings->enable_net_security_expiration =
-      settings_.enable_net_security_expiration ||
-      command_line->HasSwitch(switches::kEnableNetSecurityExpiration);
   CefString(&settings->accept_language_list) =
       CefString(&settings_.accept_language_list);
 }

libcef/common/cef_switches.cc

@@ -113,9 +113,6 @@ const char kPluginPolicy_Block[] = "block";
 // Expose preferences used only by unit tests.
 const char kEnablePreferenceTesting[] = "enable-preference-testing";
 
-// Enable date-based expiration of built in network security information.
-const char kEnableNetSecurityExpiration[] = "enable-net-security-expiration";
-
 // Enable print preview.
 extern const char kEnablePrintPreview[] = "enable-print-preview";
 

libcef/common/cef_switches.h

@@ -51,7 +51,6 @@ extern const char kPluginPolicy_Allow[];
 extern const char kPluginPolicy_Detect[];
 extern const char kPluginPolicy_Block[];
 extern const char kEnablePreferenceTesting[];
-extern const char kEnableNetSecurityExpiration[];
 extern const char kEnablePrintPreview[];
 
 #if defined(OS_MACOSX)