Move ReadFileToString to the base namespace.

remoting/protocol/ssl_hmac_channel_authenticator_unittest.cc

Index: remoting/protocol/ssl_hmac_channel_authenticator_unittest.cc
diff --git a/remoting/protocol/ssl_hmac_channel_authenticator_unittest.cc b/remoting/protocol/ssl_hmac_channel_authenticator_unittest.cc
index f93658d5d62b7566c507d8cdadb86b7edcbc39bc..abf288092506a5c5aeaff5db9bd943a3ba4caa26 100644
--- a/remoting/protocol/ssl_hmac_channel_authenticator_unittest.cc
+++ b/remoting/protocol/ssl_hmac_channel_authenticator_unittest.cc
@@ -58,11 +58,11 @@ class SslHmacChannelAuthenticatorTest : public testing::Test {
     base::FilePath certs_dir(net::GetTestCertsDirectory());
 
     base::FilePath cert_path = certs_dir.AppendASCII("unittest.selfsigned.der");
-    ASSERT_TRUE(file_util::ReadFileToString(cert_path, &host_cert_));
+    ASSERT_TRUE(base::ReadFileToString(cert_path, &host_cert_));
 
     base::FilePath key_path = certs_dir.AppendASCII("unittest.key.bin");
     std::string key_string;
-    ASSERT_TRUE(file_util::ReadFileToString(key_path, &key_string));
+    ASSERT_TRUE(base::ReadFileToString(key_path, &key_string));
     std::string key_base64;
     base::Base64Encode(key_string, &key_base64);
     key_pair_ = RsaKeyPair::FromString(key_base64);