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

components/history/core/browser/top_sites_database.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 "components/history/core/browser/top_sites_database.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/history/core/browser/top_sites.h"
 #include "components/history/core/common/thumbnail_score.h"
 #include "sql/connection.h"
 #include "sql/recovery.h"
 #include "sql/statement.h"
 #include "sql/transaction.h"
 #include "third_party/sqlite/sqlite3.h"
@@ skipping 55 matching lines @@
       "good_clipping INTEGER DEFAULT 0,"
       "at_top INTEGER DEFAULT 0,"
       "last_updated INTEGER DEFAULT 0,"
       "load_completed INTEGER DEFAULT 0,"
       "last_forced INTEGER DEFAULT 0)";
   return db->Execute(kThumbnailsSql);
 }
 
 // Encodes redirects into a string.
 std::string GetRedirects(const MostVisitedURL& url) {
-  std::vector<std::string> redirects;
-  for (size_t i = 0; i < url.redirects.size(); i++)
-    redirects.push_back(url.redirects[i].spec());
+  std::vector<base::StringPiece> redirects;
+  for (const auto& redirect : url.redirects)
+    redirects.push_back(redirect.spec());
   return base::JoinString(redirects, " ");
 }
 
 // Decodes redirects from a string and sets them for the url.
 void SetRedirects(const std::string& redirects, MostVisitedURL* url) {
   for (const std::string& redirect : base::SplitString(
            redirects, base::kWhitespaceASCII,
            base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY)) {
     GURL redirect_url(redirect);
     if (redirect_url.is_valid())
@@ skipping 624 matching lines @@
   db->set_error_callback(base::Bind(&DatabaseErrorCallback, db.get(), db_name));
   db->set_page_size(4096);
   db->set_cache_size(32);
 
   if (!db->Open(db_name))
     return NULL;
   return db.release();
 }
 
 }  // namespace history