Move more file_util functions to base namespace.

net/disk_cache/backend_unittest.cc

Index: net/disk_cache/backend_unittest.cc
diff --git a/net/disk_cache/backend_unittest.cc b/net/disk_cache/backend_unittest.cc
index c7b37e4d1eaf882da04397a36b98f379806b8f21..b25001f11d905da6896d4b997121be4decdea100 100644
--- a/net/disk_cache/backend_unittest.cc
+++ b/net/disk_cache/backend_unittest.cc
@@ -489,7 +489,7 @@ TEST_F(DiskCacheBackendTest, ExternalFiles) {
 
   // And verify that the first file is still there.
   scoped_refptr<net::IOBuffer> buffer2(new net::IOBuffer(kSize));
-  ASSERT_EQ(kSize, file_util::ReadFile(filename, buffer2->data(), kSize));
+  ASSERT_EQ(kSize, base::ReadFile(filename, buffer2->data(), kSize));
   EXPECT_EQ(0, memcmp(buffer1->data(), buffer2->data(), kSize));
 }