Reduce number of string allocations in util.cc.

components/safe_browsing_db/util.cc

 // Copyright (c) 2015 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/safe_browsing_db/util.h"
 
 #include "base/strings/string_util.h"
 #include "crypto/sha2.h"
 #include "net/base/escape.h"
 #include "url/gurl.h"
@@ skipping 212 matching lines @@
   f_replacements.ClearPassword();
   url_without_fragment = url.ReplaceComponents(f_replacements);
 
   // 2. Do URL unescaping until no more hex encoded characters exist.
   std::string url_unescaped_str(Unescape(url_without_fragment.spec()));
   url::Parsed parsed;
   url::ParseStandardURL(url_unescaped_str.data(), url_unescaped_str.length(),
                         &parsed);
 
   // 3. In hostname, remove all leading and trailing dots.
-  const std::string host =
-      (parsed.host.len > 0)
-          ? url_unescaped_str.substr(parsed.host.begin, parsed.host.len)
-          : std::string();
-  std::string host_without_end_dots;
-  base::TrimString(host, ".", &host_without_end_dots);
+  base::StringPiece host;
+  if (parsed.host.len > 0)
+    host.set(url_unescaped_str.data() + parsed.host.begin, parsed.host.len);
+
+  base::StringPiece host_without_end_dots =
+      base::TrimString(host, ".", base::TrimPositions::TRIM_ALL);
 
   // 4. In hostname, replace consecutive dots with a single dot.
   std::string host_without_consecutive_dots(RemoveConsecutiveChars(
       host_without_end_dots, '.'));
 
   // 5. In path, replace runs of consecutive slashes with a single slash.
-  std::string path =
-      (parsed.path.len > 0)
-          ? url_unescaped_str.substr(parsed.path.begin, parsed.path.len)
-          : std::string();
+  base::StringPiece path;
+  if (parsed.path.len > 0)
+    path.set(url_unescaped_str.data() + parsed.path.begin, parsed.path.len);
   std::string path_without_consecutive_slash(RemoveConsecutiveChars(path, '/'));
 
   url::Replacements<char> hp_replacements;
   hp_replacements.SetHost(
       host_without_consecutive_dots.data(),
       url::Component(0, host_without_consecutive_dots.length()));
   hp_replacements.SetPath(
       path_without_consecutive_slash.data(),
       url::Component(0, path_without_consecutive_slash.length()));
 
@@ skipping 108 matching lines @@
   GenerateHostsToCheck(url, &hosts);
   GeneratePathsToCheck(url, &paths);
   for (size_t h = 0; h < hosts.size(); ++h) {
     for (size_t p = 0; p < paths.size(); ++p) {
       urls->push_back(hosts[h] + paths[p]);
     }
   }
 }
 
 }  // namespace safe_browsing