Use plural formats and native digits

base/strings/string_number_conversions.h

Index: base/strings/string_number_conversions.h
diff --git a/base/strings/string_number_conversions.h b/base/strings/string_number_conversions.h
index 1265f0dcba3a443a16fe06e79c838e450745058c..a3b876aa155c40d3ba00bb62d5aab988723e8e31 100644
--- a/base/strings/string_number_conversions.h
+++ b/base/strings/string_number_conversions.h
@@ -25,6 +25,14 @@
 // Please do not add "convenience" functions for converting strings to integers
 // that return the value and ignore success/failure. That encourages people to
 // write code that doesn't properly handle the error conditions.
+//
+// DO NOT use these functions in any UI unless it's NOT localized on purpose.
+// Instead, use base::MessageFormatter for a complex message with numbers
+// (integer, float, double) embedded or base::Format{Number,Double,Percent} to
+// just format a single number/percent. Note that some languages use native
+// digits instead of ASCII digits while others use a group separator or decimal
+// point different from ',' and '.'. Using these functions in the UI would lead
+// numbers to be formatted in a non-native way.
 // ----------------------------------------------------------------------------
 
 namespace base {