Using STL to implement functionality in input_method_util.cc

chrome/browser/chromeos/input_method/input_method_util.cc

 // 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.
 
 #include "chrome/browser/chromeos/input_method/input_method_util.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <functional>
@@ skipping 672 matching lines @@
   std::vector<std::string>& ids = *input_method_ids;
   for (size_t i = 0; i < ids.size(); ++i) {
     std::string id = MigrateInputMethod(ids[i]);
     if (id != ids[i]) {
       ids[i] = id;
       rewritten = true;
     }
   }
   if (rewritten) {
     // Removes the duplicates.
-    std::vector<std::string> new_ids;
-    for (size_t i = 0; i < ids.size(); ++i) {
-      if (std::find(new_ids.begin(), new_ids.end(), ids[i]) == new_ids.end())
-        new_ids.push_back(ids[i]);
-    }
-    ids.swap(new_ids);
+    std::sort(ids.begin(), ids.end());

[Shu Chen, 2016/03/24 13:05:31]

The sort() here is risky since the order of the input method ids matters.

[chakshu, 2016/04/04 05:28:32]

Okay, I was not aware that the order of input method ids matters. I was
suggested to use std::unique for this
(https://codereview.chromium.org/1715683002/diff/20001/chrome/browser/chromeos...)
for which it is required to sort.

So should I use unique with some modifications so that the order is retained? Or
just roll back this change?

[Shu Chen, 2016/04/04 12:48:15]

I'm not sure whether std::unique can do the thing.
But using std::unordered_set should be enough to improve the performance here.
Thanks.

[chakshu, 2016/04/11 06:54:37]

Done !
Also if you want it to be done in-place without creating the new_ids vector but
instead erase directly in ids vector, let me know. I will make that change else
this should be fine.
Thank you.

+    ids.erase(std::unique(ids.begin(), ids.end()), ids.end());
   }
   return rewritten;
 }
 
 void InputMethodUtil::UpdateHardwareLayoutCache() {
   DCHECK(thread_checker_.CalledOnValidThread());
   hardware_layouts_.clear();
   hardware_login_layouts_.clear();
   if (cached_hardware_layouts_.empty()) {
     cached_hardware_layouts_ =
@@ skipping 117 matching lines @@
       "US",
       layouts,
       languages,
       true,  // login keyboard.
       GURL(),  // options page, not available.
       GURL()); // input view page, not available.
 }
 
 }  // namespace input_method
 }  // namespace chromeos