Move ReadFileToString to the base namespace.

chrome/test/webdriver/webdriver_util_unittest.cc

Index: chrome/test/webdriver/webdriver_util_unittest.cc
diff --git a/chrome/test/webdriver/webdriver_util_unittest.cc b/chrome/test/webdriver/webdriver_util_unittest.cc
index a888b013d5f5a8a5acd57cf5d025c510943180a1..ada282f37e8e1a677f19987b73bd3050f1d0c121 100644
--- a/chrome/test/webdriver/webdriver_util_unittest.cc
+++ b/chrome/test/webdriver/webdriver_util_unittest.cc
@@ -41,7 +41,7 @@ TEST(ZipFileTest, ZipEntryToZipArchive) {
   ASSERT_TRUE(UnzipSoleFile(temp_dir.path(), data, &file, &error_msg))
       << error_msg;
   std::string contents;
-  ASSERT_TRUE(file_util::ReadFileToString(file, &contents));
+  ASSERT_TRUE(base::ReadFileToString(file, &contents));
   ASSERT_STREQ("COW\n", contents.c_str());
 }