Replace brillo::make_unique_ptr with base::MakeUnique/base::WrapUnique.

base::MakeUnique mimics std::make_unique and is preferred over
brillo::make_unique_ptr (which is identical to base::WrapUnique).
brillo::make_unique_ptr will eventually be deprecated and removed as its
functionality is well covered by base::MakeUnique and base::WrapUnique.

BUG=chromium:704644
TEST=Run unit tests.

Change-Id: I771b312d04643a1c74dd843947ed30bda510eed2
Reviewed-on: https://chromium-review.googlesource.com/458562
Commit-Ready: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Alex Deymo <deymo@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Sen Jiang <senj@chromium.org>
diff --git a/payload_generator/mapfile_filesystem.cc b/payload_generator/mapfile_filesystem.cc
index f4f0804..5264a9c 100644
--- a/payload_generator/mapfile_filesystem.cc
+++ b/payload_generator/mapfile_filesystem.cc
@@ -21,9 +21,9 @@
 
 #include <base/files/file_util.h>
 #include <base/logging.h>
+#include <base/memory/ptr_util.h>
 #include <base/strings/string_number_conversions.h>
 #include <base/strings/string_split.h>
-#include <brillo/make_unique_ptr.h>
 
 #include "update_engine/common/utils.h"
 #include "update_engine/payload_generator/extent_ranges.h"
@@ -61,8 +61,7 @@
     return nullptr;
   }
 
-  return brillo::make_unique_ptr(
-      new MapfileFilesystem(mapfile_filename, num_blocks));
+  return base::WrapUnique(new MapfileFilesystem(mapfile_filename, num_blocks));
 }
 
 MapfileFilesystem::MapfileFilesystem(const string& mapfile_filename,