Enable (optional) blocking of webrequests in case a PAC script cannot be fetched or is invalid.

chrome/browser/extensions/extension_proxy_api.cc

 // Copyright (c) 2011 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.
 
 // Implementation of the Chrome Extensions Proxy Settings API.
 
 #include "chrome/browser/extensions/extension_proxy_api.h"
 
 #include "base/json/json_writer.h"
 #include "base/values.h"
@@ skipping 55 matching lines @@
   CHECK(extension_pref->IsType(Value::TYPE_DICTIONARY));
   const DictionaryValue* config =
       static_cast<const DictionaryValue*>(extension_pref);
 
   // Extract the various pieces of information passed to
   // chrome.experimental.proxy.settings.set(). Several of these strings will
   // remain blank no respective values have been passed to set().
   // If a values has been passed to set but could not be parsed, we bail
   // out and return NULL.
   ProxyPrefs::ProxyMode mode_enum;
+  bool pac_mandatory;
   std::string pac_url;
   std::string pac_data;
   std::string proxy_rules_string;
   std::string bypass_list;
   if (!helpers::GetProxyModeFromExtensionPref(config, &mode_enum, error) ||
+      !helpers::GetPacMandatoryFromExtensionPref(config, &pac_mandatory,
+                                                 error) ||
       !helpers::GetPacUrlFromExtensionPref(config, &pac_url, error) ||
       !helpers::GetPacDataFromExtensionPref(config, &pac_data, error) ||
       !helpers::GetProxyRulesStringFromExtensionPref(
           config, &proxy_rules_string, error) ||
       !helpers::GetBypassListFromExtensionPref(config, &bypass_list, error)) {
     return NULL;
   }
 
   return helpers::CreateProxyConfigDict(
-      mode_enum, pac_url, pac_data, proxy_rules_string, bypass_list, error);
+      mode_enum, pac_mandatory, pac_url, pac_data, proxy_rules_string,
+      bypass_list, error);
 }
 
 Value* ProxyPrefTransformer::BrowserToExtensionPref(const Value* browser_pref) {
   CHECK(browser_pref->IsType(Value::TYPE_DICTIONARY));
 
   // This is a dictionary wrapper that exposes the proxy configuration stored in
   // the browser preferences.
   ProxyConfigDictionary config(
       static_cast<const DictionaryValue*>(browser_pref));
 
@@ skipping 31 matching lines @@
       if (!proxy_rules_dict)
         return NULL;
       extension_pref->Set(keys::kProxyConfigRules, proxy_rules_dict);
       break;
     }
     case ProxyPrefs::kModeCount:
       NOTREACHED();
   }
   return extension_pref.release();
 }