Make SafeBrowsingResourceThrottleFactory::RegisterFactory() not optional.

chrome/browser/renderer_host/safe_browsing_resource_throttle_factory.h

Index: chrome/browser/renderer_host/safe_browsing_resource_throttle_factory.h
diff --git a/chrome/browser/renderer_host/safe_browsing_resource_throttle_factory.h b/chrome/browser/renderer_host/safe_browsing_resource_throttle_factory.h
index 4a37de440fb6292465ae64926069b4a4507a57c4..4c1821e0b2bee8be2bc222cc0c6f0fac545feedd 100644
--- a/chrome/browser/renderer_host/safe_browsing_resource_throttle_factory.h
+++ b/chrome/browser/renderer_host/safe_browsing_resource_throttle_factory.h
@@ -18,19 +18,15 @@ namespace net {
 class URLRequest;
 }
 
-// Factory for creating a SafeBrowsingResourceThrottle. When FULL_SAFE_BROWSING
-// is enabled, creates a SafeBrowsingResourceThrottle. When MOBILE_SAFE_BROWSING
-// is enabled, the default implementation creates a null resource throttle,
-// therefore, a factory has to be registered before using this.
+// Factory for creating a SafeBrowsingResourceThrottle. If a factory is
+// registered, the factory's CreateResourceThrottle() is called.  Otherwise,
+// when FULL_SAFE_BROWSING is enabled, a new SafeBrowsingResourceThrottle is
+// returned, or NULL if MOBILE_SAFE_BROWSING is enabled.
 class SafeBrowsingResourceThrottleFactory {
  public:
-#if defined(FULL_SAFE_BROWSING) || defined(MOBILE_SAFE_BROWSING)
   // Registers a factory. Does not take the ownership of the factory. The
   // caller has to make sure the factory stays alive and properly destroyed.
-  static void RegisterFactory(SafeBrowsingResourceThrottleFactory* factory) {
-    factory_ = factory;
-  }
-#endif
+  static void RegisterFactory(SafeBrowsingResourceThrottleFactory* factory);
 
   // Creates a new resource throttle for safe browsing
   static content::ResourceThrottle* Create(