When the download policy is specified but left empty revert to default download location.

chrome/browser/policy/configuration_policy_pref_store.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.
 
 #include "chrome/browser/policy/configuration_policy_pref_store.h"
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "base/string16.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/download/download_util.h"
 #include "chrome/browser/policy/browser_policy_connector.h"
 #include "chrome/browser/policy/configuration_policy_provider.h"
 #include "chrome/browser/policy/policy_path_parser.h"
 #include "chrome/browser/prefs/incognito_mode_prefs.h"
 #include "chrome/browser/prefs/pref_value_map.h"
 #include "chrome/browser/prefs/proxy_config_dictionary.h"
 #include "chrome/browser/search_engines/search_terms_data.h"
 #include "chrome/browser/search_engines/template_url.h"
 #include "chrome/common/pref_names.h"
 #include "content/common/notification_service.h"
@@ skipping 439 matching lines @@
   // expanded string.
   if (policy == kPolicyDownloadDirectory) {
     // This policy is ignored on ChromeOS because the download path there is
     // fixed and can not be configured by the user.
 #if !defined(OS_CHROMEOS)
     FilePath::StringType string_value;
     bool result = value->GetAsString(&string_value);
     DCHECK(result);
     FilePath::StringType expanded_value =
         policy::path_parser::ExpandPathVariables(string_value);
+    // Leaving the policy empty would revert to the default download location
+    // else we would point in an undefined location. We do this after the
+    // path expansion because it might lead to an empty string(e.g. for "\"\"").
+    if (expanded_value.empty())
+      expanded_value = download_util::GetDefaultDownloadDirectory().value();
     prefs_.SetValue(prefs::kDownloadDefaultDirectory,
                     Value::CreateStringValue(expanded_value));
     prefs_.SetValue(prefs::kPromptForDownload,
                     Value::CreateBooleanValue(false));
 #endif  // !defined(OS_CHROMEOS)
     delete value;
     return true;
   }
   // We are not interested in this policy.
   return false;
@@ skipping 715 matching lines @@
   // Update the initialization flag.
   if (!initialization_complete_ &&
       provider_->IsInitializationComplete()) {
     initialization_complete_ = true;
     FOR_EACH_OBSERVER(PrefStore::Observer, observers_,
                       OnInitializationCompleted(true));
   }
 }
 
 }  // namespace policy