Change other usages of .size() to .empty() when applicable.

chrome/browser/download/download_util.cc

 // Copyright (c) 2011 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.
 //
 // Download utility implementation
 
 #include "chrome/browser/download/download_util.h"
 
 #if defined(OS_WIN)
 #include <shobjidl.h>
@@ skipping 95 matching lines @@
   };
 
   for (int i = 0; i < arraysize(integrated_extensions); ++i) {
     if (extension_lower == integrated_extensions[i])
       return true;
   }
 
   // See <http://www.juniper.net/security/auto/vulnerabilities/vuln2612.html>.
   // That vulnerability report is not exactly on point, but files become magical
   // if their end in a CLSID.  Here we block extensions that look like CLSIDs.
-  if (extension_lower.size() > 0 && extension_lower.at(0) == L'{' &&
-      extension_lower.at(extension_lower.length() - 1) == L'}')
+  if (!extension_lower.empty() && extension_lower[0] == L'{' &&
+      extension_lower[extension_lower.length() - 1] == L'}')
     return true;
 
   return false;
 }
 
 // Returns whether the specified file name is a reserved name on windows.
 // This includes names like "com2.zip" (which correspond to devices) and
 // desktop.ini and thumbs.db which have special meaning to the windows shell.
 bool IsReservedName(const string16& filename) {
   // This list is taken from the MSDN article "Naming a file"
@@ skipping 704 matching lines @@
         !service->IsDownloadFromGallery(info->url, info->referrer_url)) {
       // Extensions that are not from the gallery are considered dangerous.
       ret = true;
     }
   }
 
   return ret;
 }
 
 }  // namespace download_util