Move WriteInto to base namespace.

net/base/net_string_util_icu.cc

Index: net/base/net_string_util_icu.cc
diff --git a/net/base/net_string_util_icu.cc b/net/base/net_string_util_icu.cc
index 435f9de24888faec5b93e9a3ca1df4858c73d1c2..525800c90df61c20c1e4151943cffd36bf6c9de7 100644
--- a/net/base/net_string_util_icu.cc
+++ b/net/base/net_string_util_icu.cc
@@ -27,7 +27,7 @@ bool ConvertToUtf8(const std::string& text, const char* charset,
   // in UTF-8. Therefore, the expansion ratio is 3 at most. Add one for a
   // trailing '\0'.
   size_t output_length = text.length() * 3 + 1;
-  char* buf = WriteInto(output, output_length);
+  char* buf = base::WriteInto(output, output_length);
   output_length = ucnv_toAlgorithmic(UCNV_UTF8, converter, buf, output_length,
                                      text.data(), text.length(), &err);
   ucnv_close(converter);