Don't check URLs against Safe Browsing if not supported.

chrome/browser/safe_browsing/local_database_manager.h

 // 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.
 //
 // Safe Browsing Database Manager implementation that manages a local
 // database.  This is used by Desktop Chromium.
 
 #ifndef CHROME_BROWSER_SAFE_BROWSING_LOCAL_DATABASE_MANAGER_H_
 #define CHROME_BROWSER_SAFE_BROWSING_LOCAL_DATABASE_MANAGER_H_
 
@@ skipping 83 matching lines @@
   };
 
   // Creates the safe browsing service.  Need to initialize before using.
   explicit LocalSafeBrowsingDatabaseManager(
       const scoped_refptr<SafeBrowsingService>& service);
 
   //
   // SafeBrowsingDatabaseManager overrides
   //
 
+  bool IsSupported() const override;
   bool CanCheckUrl(const GURL& url) const override;
 
   bool CheckBrowseUrl(const GURL& url, Client* client) override;
   bool CheckDownloadUrl(const std::vector<GURL>& url_chain,
                         Client* client) override;
   bool CheckExtensionIDs(const std::set<std::string>& extension_ids,
                          Client* client) override;
   bool MatchCsdWhitelistUrl(const GURL& url) override;
   bool MatchMalwareIP(const std::string& ip_address) override;
   bool MatchDownloadWhitelistUrl(const GURL& url) override;
@@ skipping 238 matching lines @@
 
   std::deque<QueuedCheck> queued_checks_;
 
   // Timeout to use for safe browsing checks.
   base::TimeDelta check_timeout_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalSafeBrowsingDatabaseManager);
 };  // class LocalSafeBrowsingDatabaseManager
 
 #endif  // CHROME_BROWSER_SAFE_BROWSING_LOCAL_DATABASE_MANAGER_H_