Change uses of base::JoinString to pass StringPieces where possible.

chrome/browser/extensions/content_capabilities_browsertest.cc

 // Copyright 2014 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 <string>
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/path_service.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/extensions/test_extension_dir.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "components/crx_file/id_util.h"
 #include "content/public/test/browser_test_utils.h"
@@ skipping 38 matching lines @@
         "  \"permissions\": %s\n"
         "}\n",
         matches.c_str(), permissions.c_str(), extension_permissions.c_str());
     test_extension_dir_.WriteManifest(manifest);
     return LoadExtension(test_extension_dir_.UnpackedPath());
   }
 
   std::string MakeJSONList(const std::string& s0 = "",
                            const std::string& s1 = "",
                            const std::string& s2 = "") {
-    std::vector<std::string> v;
+    std::vector<base::StringPiece> v;
     if (!s0.empty())
       v.push_back(s0);
     if (!s1.empty())
       v.push_back(s1);
     if (!s2.empty())
       v.push_back(s2);
     std::string list = base::JoinString(v, "\",\"");
     if (!list.empty())
       list = "\"" + list + "\"";
     return "[" + list + "]";
@@ skipping 175 matching lines @@
   // This extension has unlimitedStorage but doesn't grant it to foo.example.com
   scoped_refptr<const Extension> extension = LoadExtensionWithCapabilities(
       MakeJSONList("http://foo.example.com/*"), MakeJSONList("clipboardRead"),
       MakeJSONList("unlimitedStorage"));
 
   EXPECT_TRUE(
       HasUnlimitedStorage(extension.get(), extension->GetResourceURL("")));
   EXPECT_FALSE(
       HasUnlimitedStorage(extension.get(), GetTestURLFor("foo.example.com")));
 }