Improve the UI for disabling off-store extension install.

chrome/common/extensions/extension_switch_utils.cc

 // 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.
 
 #include "chrome/common/extensions/extension_switch_utils.h"
 
 #include "base/command_line.h"
 #include "chrome/common/chrome_switches.h"
 
 namespace extensions {
 
 namespace switch_utils {
 
 bool IsOffStoreInstallEnabled() {
   // Disabling off-store installation is not yet implemented for Aura. Not sure
   // what the Aura equivalent for this UI is.
 #if defined(USE_AURA)
   return true;
 #else
-  return CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableOffStoreExtensionInstall);
+  // Currently, we default to enabling off-store install.
+  std::string switch_value =
+      CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          switches::kEnableOffStoreExtensionInstall);
+  return switch_value != "0";
 #endif
 }
 
 bool IsActionBoxEnabled() {
   return CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableActionBox);
 }
 
 }  // switch_utils
 
 }  // extensions