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

chrome/browser/extensions/webstore_installer.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 "chrome/browser/extensions/webstore_installer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <limits>
 #include <set>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/path_service.h"
 #include "base/rand_util.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 "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/download/download_crx_util.h"
 #include "chrome/browser/download/download_prefs.h"
 #include "chrome/browser/download/download_stats.h"
 #include "chrome/browser/extensions/crx_installer.h"
@@ skipping 173 matching lines @@
       install_source = kDefaultInstallSource;
   }
 
   base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
   if (cmd_line->HasSwitch(switches::kAppsGalleryDownloadURL)) {
     std::string download_url =
         cmd_line->GetSwitchValueASCII(switches::kAppsGalleryDownloadURL);
     return GURL(base::StringPrintf(download_url.c_str(),
                                    extension_id.c_str()));
   }
-  std::vector<std::string> params;
-  params.push_back("id=" + extension_id);
+  std::vector<base::StringPiece> params;
+  std::string extension_param = "id=" + extension_id;
+  std::string installsource_param = "installsource=" + install_source;
+  params.push_back(extension_param);
   if (!install_source.empty())
-    params.push_back("installsource=" + install_source);
+    params.push_back(installsource_param);
   params.push_back("uc");
   std::string url_string = extension_urls::GetWebstoreUpdateUrl().spec();
 
   GURL url(url_string + "?response=redirect&" +
            update_client::UpdateQueryParams::Get(
                update_client::UpdateQueryParams::CRX) +
            "&x=" + net::EscapeQueryParamValue(base::JoinString(params, "&"),
                                               true));
   DCHECK(url.is_valid());
 
@@ skipping 556 matching lines @@
         1,
         kMaxSizeKb,
         kNumBuckets);
   }
   UMA_HISTOGRAM_BOOLEAN(
       "Extensions.WebstoreDownload.InterruptTotalSizeUnknown",
       total_bytes <= 0);
 }
 
 }  // namespace extensions