libchromeos: Migrate string_utils from Buffet to libchromeos

BUG=chromium:405714
TEST=USE=buffet ./build_packages

Change-Id: I95d8977aed6ffd718751de058d4cdda3a5395c25
Reviewed-on: https://chromium-review.googlesource.com/213361
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/commands/command_queue_unittest.cc b/buffet/commands/command_queue_unittest.cc
index 2c0e01b..a9d5ad9 100644
--- a/buffet/commands/command_queue_unittest.cc
+++ b/buffet/commands/command_queue_unittest.cc
@@ -6,11 +6,11 @@
 #include <string>
 #include <vector>
 
+#include <chromeos/string_utils.h>
 #include <gtest/gtest.h>
 
 #include "buffet/commands/command_dispatch_interface.h"
 #include "buffet/commands/command_queue.h"
-#include "buffet/string_utils.h"
 
 namespace {
 
@@ -46,7 +46,7 @@
   // Get the comma-separated list of command IDs currently accumulated in the
   // command queue.
   std::string GetIDs() const {
-    using buffet::string_utils::Join;
+    using chromeos::string_utils::Join;
     return Join(',', std::vector<std::string>(ids_.begin(), ids_.end()));
   }
 
@@ -99,7 +99,7 @@
   std::string id1 = queue.Add(CreateDummyCommandInstance());
   std::string id2 = queue.Add(CreateDummyCommandInstance());
   std::set<std::string> ids{id1, id2};  // Make sure they are sorted properly.
-  std::string expected_set = buffet::string_utils::Join(
+  std::string expected_set = chromeos::string_utils::Join(
       ',', std::vector<std::string>(ids.begin(), ids.end()));
   EXPECT_EQ(expected_set, dispatch.GetIDs());
   queue.Remove(id1);