Move ReadFileToString to the base namespace.

chrome/browser/chromeos/drive/file_cache_unittest.cc

Index: chrome/browser/chromeos/drive/file_cache_unittest.cc
diff --git a/chrome/browser/chromeos/drive/file_cache_unittest.cc b/chrome/browser/chromeos/drive/file_cache_unittest.cc
index 7c7b947e2778cfe790dd7295d566f671faf8ce74..205271ca1f538094d322bfd140cbaa0258ddae16 100644
--- a/chrome/browser/chromeos/drive/file_cache_unittest.cc
+++ b/chrome/browser/chromeos/drive/file_cache_unittest.cc
@@ -918,11 +918,11 @@ TEST_F(FileCacheTest, RenameCacheFilesToNewFormat) {
   // Rename and verify the result.
   RenameCacheFilesToNewFormat(cache_.get());
   std::string contents;
-  EXPECT_TRUE(file_util::ReadFileToString(file_directory.AppendASCII("id_koo"),
+  EXPECT_TRUE(base::ReadFileToString(file_directory.AppendASCII("id_koo"),
                                           &contents));
   EXPECT_EQ("koo", contents);
   contents.clear();
-  EXPECT_TRUE(file_util::ReadFileToString(file_directory.AppendASCII("id_kyu"),
+  EXPECT_TRUE(base::ReadFileToString(file_directory.AppendASCII("id_kyu"),
                                           &contents));
   EXPECT_EQ("kyu", contents);
 
@@ -931,11 +931,11 @@ TEST_F(FileCacheTest, RenameCacheFilesToNewFormat) {
 
   // Files with new style names are not affected.
   contents.clear();
-  EXPECT_TRUE(file_util::ReadFileToString(file_directory.AppendASCII("id_koo"),
+  EXPECT_TRUE(base::ReadFileToString(file_directory.AppendASCII("id_koo"),
                                           &contents));
   EXPECT_EQ("koo", contents);
   contents.clear();
-  EXPECT_TRUE(file_util::ReadFileToString(file_directory.AppendASCII("id_kyu"),
+  EXPECT_TRUE(base::ReadFileToString(file_directory.AppendASCII("id_kyu"),
                                           &contents));
   EXPECT_EQ("kyu", contents);
 }