Update from https://crrev.com/304121

base/base64_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/base64.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
 TEST(Base64Test, Basic) {
   const std::string kText = "hello world";
   const std::string kBase64Text = "aGVsbG8gd29ybGQ=";
 
   std::string encoded;
   std::string decoded;
   bool ok;
 
   Base64Encode(kText, &encoded);
   EXPECT_EQ(kBase64Text, encoded);
 
   ok = Base64Decode(encoded, &decoded);
   EXPECT_TRUE(ok);
   EXPECT_EQ(kText, decoded);
 }
 
+TEST(Base64Test, InPlace) {
+  const std::string kText = "hello world";
+  const std::string kBase64Text = "aGVsbG8gd29ybGQ=";
+  std::string text(kText);
+
+  Base64Encode(text, &text);
+  EXPECT_EQ(kBase64Text, text);
+
+  bool ok = Base64Decode(text, &text);
+  EXPECT_TRUE(ok);
+  EXPECT_EQ(text, kText);
+}
+
 }  // namespace base