Manuarlly remove more deprecated forms of base::Base64Encode()

This CL should remove the remaining instances, but stops short of
actually removing the deprecated form itself.

Bug: 1486214
Change-Id: Id27d692d7303de538f2c7fa1978800169615024b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5247305
Owners-Override: Daniel Cheng <[email protected]>
Commit-Queue: Tom Sepez <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1255101}
diff --git a/components/variations/variations_test_utils_unittest.cc b/components/variations/variations_test_utils_unittest.cc
index b2e82929..5d4d9c82 100644
--- a/components/variations/variations_test_utils_unittest.cc
+++ b/components/variations/variations_test_utils_unittest.cc
@@ -28,9 +28,8 @@
   ASSERT_TRUE(compression::GzipUncompress(decoded_compressed_data,
                                           &actual_uncompressed_data));
 
-  std::string actual_encoded_uncompressed_data;
-  base::Base64Encode(actual_uncompressed_data,
-                     &actual_encoded_uncompressed_data);
+  std::string actual_encoded_uncompressed_data =
+      base::Base64Encode(actual_uncompressed_data);
   EXPECT_EQ(actual_encoded_uncompressed_data,
             signed_seed_data.base64_uncompressed_data);