Declare a variable before using it

components/autofill/core/browser/personal_data_manager.cc

 // Copyright 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 "components/autofill/core/browser/personal_data_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 862 matching lines @@
       unique_matched_profiles, &other_field_types, type.GetStorableType(), 1,
       app_locale_, &labels);
   DCHECK_EQ(unique_suggestions.size(), labels.size());
   for (size_t i = 0; i < labels.size(); i++)
     unique_suggestions[i].label = labels[i];
 
   // Get the profile suggestions limit value set for the current frecency field
   // trial group or SIZE_MAX if no limit is defined.
   std::string limit_str = variations::GetVariationParamValue(
       kFrecencyFieldTrialName, kFrecencyFieldTrialLimitParam);
-  size_t limit = base::StringToSizeT(limit_str, &limit) ? limit : SIZE_MAX;
+  size_t limit;

[vabr (Chromium), 2017/03/04 19:40:29]

This is actually worse than before. Before there was not a single point in the
code where |limit| would not be initialised. Now the declaration and assignment
are separate, and if somebody adds code between them, there will be a
non-trivial interval of |limit| having an undefined value.

Please either revert to the previous state, or initialize limit. A good default
value is SIZE_MAX. Note that you also still need to keep the assignment after
calling StringToSizeT, because that method can modify |limit| even if it returns
false. This would be good to capture in a comment here as well.

size_t limit = SIZE_MAX;

[chengx, 2017/03/06 18:26:14]

I will use another CL to fix this. Thanks!

[vabr (Chromium), 2017/03/06 18:46:48]

SGTM, thanks for following up! :)

+  if (!base::StringToSizeT(limit_str, &limit))
+    limit = SIZE_MAX;
 
   unique_suggestions.resize(std::min(unique_suggestions.size(), limit));
 
   return unique_suggestions;
 }
 
 // TODO(crbug.com/613187): Investigate if it would be more efficient to dedupe
 // with a vector instead of a list.
 const std::vector<CreditCard*> PersonalDataManager::GetCreditCardsToSuggest()
     const {
@@ skipping 1045 matching lines @@
       existing_profiles->back().SetRawInfo(EMAIL_ADDRESS, email);
 
     AutofillMetrics::LogWalletAddressConversionType(
         AutofillMetrics::CONVERTED_ADDRESS_ADDED);
   }
 
   return guid;
 }
 
 }  // namespace autofill