Take advantage of some newer optimizations of FindFirstFile.

base/files/file_enumerator_win.cc

 // Copyright (c) 2013 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 "base/files/file_enumerator.h"
 
 #include <string.h>
 
 #include "base/logging.h"
 #include "base/threading/thread_restrictions.h"
+#include "base/win/windows_version.h"
 
 namespace base {
 
 // FileEnumerator::FileInfo ----------------------------------------------------
 
 FileEnumerator::FileInfo::FileInfo() {
   memset(&find_data_, 0, sizeof(find_data_));
 }
 
 bool FileEnumerator::FileInfo::IsDirectory() const {
@@ skipping 71 matching lines @@
       pending_paths_.pop();
 
       // Start a new find operation.
       FilePath src = root_path_;
 
       if (pattern_.empty())
         src = src.Append(L"*");  // No pattern = match everything.
       else
         src = src.Append(pattern_);
 
-      find_handle_ = FindFirstFile(src.value().c_str(), &find_data_);
+      if (base::win::GetVersion() >= base::win::VERSION_WIN7) {
+        // Use a "large fetch" on newer Windows which should speed up large
+        // enumerations (we seldom abort in the middle).
+        find_handle_ = FindFirstFileEx(src.value().c_str(),
+                                       FindExInfoBasic,  // Omit short name.
+                                       &find_data_,
+                                       FindExSearchNameMatch,
+                                       NULL,
+                                       FIND_FIRST_EX_LARGE_FETCH);
+      } else {
+        find_handle_ = FindFirstFile(src.value().c_str(), &find_data_);
+      }
       has_find_data_ = true;
     } else {
       // Search for the next file/directory.
       if (!FindNextFile(find_handle_, &find_data_)) {
         FindClose(find_handle_);
         find_handle_ = INVALID_HANDLE_VALUE;
       }
     }
 
     if (INVALID_HANDLE_VALUE == find_handle_) {
@@ skipping 29 matching lines @@
         return cur_file;
     } else if (file_type_ & FileEnumerator::FILES) {
       return cur_file;
     }
   }
 
   return FilePath();
 }
 
 }  // namespace base