Using STL to implement functionality in input_method_util.cc

chrome/browser/chromeos/input_method/input_method_util.cc

Index: chrome/browser/chromeos/input_method/input_method_util.cc
diff --git a/chrome/browser/chromeos/input_method/input_method_util.cc b/chrome/browser/chromeos/input_method/input_method_util.cc
index 97971601d00109f31cc9f2091f85829bdd351d2a..432653aadf8ddbae35de4bc45c3b0c8b9d902848 100644
--- a/chrome/browser/chromeos/input_method/input_method_util.cc
+++ b/chrome/browser/chromeos/input_method/input_method_util.cc
@@ -690,12 +690,8 @@ bool InputMethodUtil::MigrateInputMethods(
   }
   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;
 }