[autofill] Query credit card scanning feature once per browser process.

chrome/browser/ui/autofill/credit_card_scanner_controller.cc

 // Copyright 2014 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/ui/autofill/credit_card_scanner_controller.h"
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 55 matching lines @@
   // The time when the UI was shown.
   base::TimeTicks show_time_;
 
   DISALLOW_COPY_AND_ASSIGN(Controller);
 };
 
 }  // namespace
 
 // static
 bool CreditCardScannerController::HasCreditCardScanFeature() {
-  return CreditCardScannerView::CanShow();
+  static const bool kCanShow = CreditCardScannerView::CanShow();
+  return kCanShow;
 }
 
 // static
 void CreditCardScannerController::ScanCreditCard(
     content::WebContents* web_contents,
     const AutofillClient::CreditCardScanCallback& callback) {
   (new Controller(web_contents, callback))->Show();
 }
 
 }  // namespace autofill