[cleanup] Use base::nullopt in //net/proxy_resolution

Change-Id: I2451fcbfd31bb70628d138838ec95327cb8af91b
Reviewed-on: https://chromium-review.googlesource.com/1066599Reviewed-by: Bence Béky <bnc@chromium.org>
Commit-Queue: Eric Roman <eroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560334}

net/proxy_resolution/proxy_config_service_linux.cc

@@ -1026,7 +1026,7 @@ ProxyConfigServiceLinux::Delegate::GetConfigFromSettings() {
   if (!setting_getter_->GetString(SettingGetter::PROXY_MODE, &mode)) {
     // We expect this to always be set, so if we don't see it then we probably
     // have a gsettings problem, and so we don't have a valid proxy config.
-    return base::Optional<ProxyConfigWithAnnotation>();
+    return base::nullopt;
   }
   if (mode == "none") {
     // Specifically specifies no proxy.
@@ -1045,7 +1045,7 @@ ProxyConfigServiceLinux::Delegate::GetConfigFromSettings() {
           pac_url_str = "file://" + pac_url_str;
         GURL pac_url(pac_url_str);
         if (!pac_url.is_valid())
-          return base::Optional<ProxyConfigWithAnnotation>();
+          return base::nullopt;
         config.set_pac_url(pac_url);
         return ProxyConfigWithAnnotation(
             config, NetworkTrafficAnnotationTag(traffic_annotation_));
@@ -1058,7 +1058,7 @@ ProxyConfigServiceLinux::Delegate::GetConfigFromSettings() {
 
   if (mode != "manual") {
     // Mode is unrecognized.
-    return base::Optional<ProxyConfigWithAnnotation>();
+    return base::nullopt;
   }
   bool use_http_proxy;
   if (setting_getter_->GetBool(SettingGetter::PROXY_USE_HTTP_PROXY,
@@ -1122,7 +1122,7 @@ ProxyConfigServiceLinux::Delegate::GetConfigFromSettings() {
 
   if (config.proxy_rules().empty()) {
     // Manual mode but we couldn't parse any rules.
-    return base::Optional<ProxyConfigWithAnnotation>();
+    return base::nullopt;
   }
 
   // Check for authentication, just so we can warn.
@@ -1235,7 +1235,7 @@ void ProxyConfigServiceLinux::Delegate::SetUpAndFetchInitialConfig(
   // does so even if the proxy mode is set to auto, which would
   // mislead us.
 
-  cached_config_ = base::Optional<ProxyConfigWithAnnotation>();
+  cached_config_ = base::nullopt;
   if (setting_getter_ && setting_getter_->Init(glib_task_runner)) {
     cached_config_ = GetConfigFromSettings();
   }

net/proxy_resolution/proxy_resolution_service.cc

@@ -1487,9 +1487,9 @@ ProxyResolutionService::State ProxyResolutionService::ResetProxyConfig(
   init_proxy_resolver_.reset();
   SuspendAllPendingRequests();
   resolver_.reset();
-  config_ = base::Optional<ProxyConfigWithAnnotation>();
+  config_ = base::nullopt;
   if (reset_fetched_config)
-    fetched_config_ = base::Optional<ProxyConfigWithAnnotation>();
+    fetched_config_ = base::nullopt;
   current_state_ = STATE_NONE;
 
   return previous_state;