importer: Cleanup, remove all remaining using declarations.

chrome/browser/importer/mork_reader.cc

Index: chrome/browser/importer/mork_reader.cc
diff --git a/chrome/browser/importer/mork_reader.cc b/chrome/browser/importer/mork_reader.cc
index 7c6cca834cb8ac5b814c823ae6d6f8f96f1853d5..297cf3d721c6b7658dec6936e5294d3404fc75f1 100644
--- a/chrome/browser/importer/mork_reader.cc
+++ b/chrome/browser/importer/mork_reader.cc
@@ -55,8 +55,6 @@
 #include "chrome/browser/importer/firefox_importer_utils.h"
 #include "chrome/browser/importer/importer_bridge.h"
 
-using base::Time;
-
 namespace {
 
 // Convert a hex character (0-9, A-F) to its corresponding byte value.
@@ -534,7 +532,7 @@ void AddToHistory(MorkReader::ColumnDataList* column_values,
     int64 date;
     base::StringToInt64(values[kLastVisitColumn], &date);
     if (date != 0)
-      row.set_last_visit(Time::FromTimeT(date / 1000000));
+      row.set_last_visit(base::Time::FromTimeT(date / 1000000));
 
     bool is_typed = (values[kTypedColumn] == "1");
     if (is_typed)