Supervised user whitelists optimization: Store raw sha1 hashes rather than strings

chrome/browser/supervised_user/supervised_user_site_list.h

 // 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.
 
 #ifndef CHROME_BROWSER_SUPERVISED_USER_SUPERVISED_USER_SITE_LIST_H_
 #define CHROME_BROWSER_SUPERVISED_USER_SUPERVISED_USER_SITE_LIST_H_
 
+#include <array>
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/sha1.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "url/gurl.h"
 
 class Profile;
 
 namespace base {
 class DictionaryValue;
 class ListValue;
 class Value;
 }
 
 // This class represents the content of a supervised user whitelist. It is
 // loaded from a JSON file inside the extension bundle, which defines the sites
 // on the list.
 // All whitelists are combined in the SupervisedUserURLFilter, which can tell
 // for a given URL if it is part of any whitelist. Effectively,
 // SupervisedUserURLFilter then acts as a big whitelist which is the union of
 // all the whitelists.
 class SupervisedUserSiteList
     : public base::RefCountedThreadSafe<SupervisedUserSiteList> {
  public:
+  class HostnameHash {
+   public:
+    explicit HostnameHash(const std::string& hostname);
+    // |bytes| must have a size of at least |base::kSHA1Length|.
+    explicit HostnameHash(const std::vector<uint8>& bytes);
+
+    bool operator==(const HostnameHash& rhs) const;
+
+    // Returns a hash code suitable for putting this into hash maps.
+    size_t hash() const;
+
+   private:
+    std::array<uint8, base::kSHA1Length> bytes_;
+    // Copy and assign are allowed.
+  };
+
   using LoadedCallback =
       base::Callback<void(const scoped_refptr<SupervisedUserSiteList>&)>;
 
   // Asynchronously loads the site list from |file| and calls |callback| with
   // the newly created object.
   static void Load(const base::string16& title,
                    const base::FilePath& file,
                    const LoadedCallback& callback);
 
   const base::string16& title() const { return title_; }
   const GURL& entry_point() const { return entry_point_; }
   const std::vector<std::string>& patterns() const { return patterns_; }
-  const std::vector<std::string>& hostname_hashes() const {
+  const std::vector<HostnameHash>& hostname_hashes() const {
     return hostname_hashes_;
   }
 
  private:
   friend class base::RefCountedThreadSafe<SupervisedUserSiteList>;
 
   SupervisedUserSiteList(const base::string16& title,
                          const GURL& entry_point,
                          const base::ListValue* patterns,
                          const base::ListValue* hostname_hashes);
   ~SupervisedUserSiteList();
 
   // Static private so it can access the private constructor.
   static void OnJsonLoaded(
       const base::string16& title,
       const base::FilePath& path,
       base::TimeTicks start_time,
       const SupervisedUserSiteList::LoadedCallback& callback,
       scoped_ptr<base::Value> value);
 
   base::string16 title_;
   GURL entry_point_;
 
   // A list of URL patterns that should be whitelisted.
   std::vector<std::string> patterns_;
 
-  // A list of hex-encoded SHA1 hashes of hostnames that should be whitelisted.
-  std::vector<std::string> hostname_hashes_;
+  // A list of SHA1 hashes of hostnames that should be whitelisted.
+  std::vector<HostnameHash> hostname_hashes_;
 
   DISALLOW_COPY_AND_ASSIGN(SupervisedUserSiteList);
 };
 
 #endif  // CHROME_BROWSER_SUPERVISED_USER_SUPERVISED_USER_SITE_LIST_H_