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

chrome/browser/safe_browsing/remote_database_manager.cc

 // Copyright 2015 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/safe_browsing/remote_database_manager.h"
 
 #include <vector>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/timer/elapsed_timer.h"
@@ skipping 68 matching lines @@
 // TODO(nparker): Add tests for this class
 RemoteSafeBrowsingDatabaseManager::RemoteSafeBrowsingDatabaseManager()
     : enabled_(false) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 }
 
 RemoteSafeBrowsingDatabaseManager::~RemoteSafeBrowsingDatabaseManager() {
   DCHECK(!enabled_);
 }
 
+bool RemoteSafeBrowsingDatabaseManager::IsSupported() const {
+  return SafeBrowsingApiHandler::GetInstance() != nullptr;
+}
+
 bool RemoteSafeBrowsingDatabaseManager::CanCheckUrl(const GURL& url) const {
   return url.SchemeIs(url::kHttpsScheme) || url.SchemeIs(url::kHttpScheme) ||
          url.SchemeIs(url::kFtpScheme);
 }
 
 bool RemoteSafeBrowsingDatabaseManager::download_protection_enabled()
     const {
   return false;
 }
 
@@ skipping 59 matching lines @@
   bool can_check_url = CanCheckUrl(url);
   UMA_HISTOGRAM_BOOLEAN("SB2.RemoteCall.CanCheckUrl", can_check_url);
   if (!can_check_url)
     return true;  // Safe, continue right away.
 
   scoped_ptr<ClientRequest> req(new ClientRequest(client, this, url));
   std::vector<SBThreatType> threat_types;  // Not currently used.
 
   DVLOG(1) << "Checking for client " << client << " and URL " << url;
   SafeBrowsingApiHandler* api_handler = SafeBrowsingApiHandler::GetInstance();
-  // If your build hits this at run time, then you should have either not built
-  // with safe_browsing=3, or set a SafeBrowingApiHandler singleton at startup.
+  // This shouldn't happen since SafeBrowsingResourceThrottle checks
+  // IsSupported() ealier.
   DCHECK(api_handler) << "SafeBrowsingApiHandler was never constructed";
   api_handler->StartURLCheck(
       base::Bind(&ClientRequest::OnRequestDoneWeak, req->GetWeakPtr()), url,
       threat_types);
 
   UMA_HISTOGRAM_COUNTS_10000("SB2.RemoteCall.ChecksPending",
                              current_requests_.size());
   current_requests_.push_back(req.release());
 
   // Defer the resource load.
@@ skipping 28 matching lines @@
   // Call back and delete any remaining clients. OnRequestDone() modifies
   // |current_requests_|, so we make a copy first.
   std::vector<ClientRequest*> to_callback(current_requests_);
   for (auto req : to_callback) {
     DVLOG(1) << "Stopping: Invoking unfinished req for URL " << req->url();
     req->OnRequestDone(SB_THREAT_TYPE_SAFE, std::string());
   }
   enabled_ = false;
 }