Make SafeBrowsingResourceThrottleFactory::RegisterFactory() not optional.

chrome/browser/renderer_host/safe_browsing_resource_throttle_factory.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/browser/renderer_host/safe_browsing_resource_throttle_factory.h"
 
 #include "content/public/browser/resource_context.h"
 #if defined(FULL_SAFE_BROWSING)
 #include "chrome/browser/renderer_host/safe_browsing_resource_throttle.h"
 #endif
 
 using content::ResourceThrottle;
 
 // static
 SafeBrowsingResourceThrottleFactory*
     SafeBrowsingResourceThrottleFactory::factory_ = NULL;
 
 // static
+void SafeBrowsingResourceThrottleFactory::RegisterFactory(
+    SafeBrowsingResourceThrottleFactory* factory) {
+  factory_ = factory;
+}
+
+// static
 ResourceThrottle* SafeBrowsingResourceThrottleFactory::Create(
     net::URLRequest* request,
     content::ResourceContext* resource_context,
     bool is_subresource,
     SafeBrowsingService* service) {
-
-#if defined(FULL_SAFE_BROWSING)
   if (factory_)
     return factory_->CreateResourceThrottle(
         request, resource_context, is_subresource, service);
+
+#if defined(FULL_SAFE_BROWSING)
   return new SafeBrowsingResourceThrottle(request, is_subresource, service);
 #elif defined(MOBILE_SAFE_BROWSING)
-  if (factory_)
-    return factory_->CreateResourceThrottle(
-        request, resource_context, is_subresource, service);
   return NULL;
 #else
 #error Need to define {FULL|MOBILE} SAFE_BROWSING mode.
 #endif
 }