Improve performance of registering font preferences

chrome/browser/ui/prefs/prefs_tab_helper.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/ui/prefs/prefs_tab_helper.h"
 
 #include <string>
 
 #include "base/prefs/overlay_user_pref_store.h"
 #include "base/string_util.h"
@@ skipping 104 matching lines @@
   prefs::kWebKitPluginsEnabled,
   prefs::kWebkitTabsToLinks,
   prefs::kWebKitUsesUniversalDetector
 };
 
 const int kPrefsToObserveLength = arraysize(kPrefsToObserve);
 
 // Registers a preference under the path |map_name| for each script used for
 // per-script font prefs.  For example, if |map_name| is "fonts.serif", then
 // "fonts.serif.Arab", "fonts.serif.Hang", etc. are registered.
-void RegisterFontFamilyMap(PrefService* prefs, const char* map_name) {
+void RegisterFontFamilyMap(PrefService* prefs,
+                           const char* map_name,
+                           const std::set<std::string>& fonts_with_defaults) {
   for (size_t i = 0; i < prefs::kWebKitScriptsForFontFamilyMapsLength; ++i) {
     const char* script = prefs::kWebKitScriptsForFontFamilyMaps[i];
     std::string pref_name_str = base::StringPrintf("%s.%s", map_name, script);
     const char* pref_name = pref_name_str.c_str();
-    if (!prefs->FindPreference(pref_name))
+    if (fonts_with_defaults.find(pref_name) == fonts_with_defaults.end()) {
+      // We haven't already set a default value for this font preference, so set
+      // an empty string as the default.
       prefs->RegisterStringPref(pref_name, "", PrefService::UNSYNCABLE_PREF);
+    }
   }
 }
 
 // Registers |obs| to observe per-script font prefs under the path |map_name|.
 void RegisterFontFamilyMapObserver(PrefChangeRegistrar* registrar,
                                    const char* map_name,
                                    content::NotificationObserver* obs) {
   for (size_t i = 0; i < prefs::kWebKitScriptsForFontFamilyMapsLength; ++i) {
     const char* script = prefs::kWebKitScriptsForFontFamilyMaps[i];
     std::string pref_name = base::StringPrintf("%s.%s", map_name, script);
@@ skipping 319 matching lines @@
   // Not used in OSX.
   prefs->RegisterLocalizedStringPref(prefs::kAcceptLanguages,
                                      IDS_ACCEPT_LANGUAGES,
                                      PrefService::UNSYNCABLE_PREF);
 #endif
   prefs->RegisterLocalizedStringPref(prefs::kDefaultCharset,
                                      IDS_DEFAULT_ENCODING,
                                      PrefService::SYNCABLE_PREF);
 
   // Register font prefs that have defaults.
+  std::set<std::string> fonts_with_defaults;
   UScriptCode browser_script = GetScriptOfBrowserLocale();
   for (size_t i = 0; i < kFontDefaultsLength; ++i) {
     const FontDefault& pref = kFontDefaults[i];
     UScriptCode pref_script = GetScriptOfFontPref(pref.pref_name);
 
     // Suppress this default font pref value if it is for the primary script of
     // the browser's UI locale.  For example, if the pref is for the sans-serif
     // font for the Cyrillic script, and the browser locale is "ru" (Russian),
     // the default is suppressed.  Otherwise, the default would override the
     // user's font preferences when viewing pages in their native language.
     // This is because users have no way yet of customizing their per-script
     // font preferences.  The font prefs accessible in the options UI are for
     // the default, unknown script; these prefs have less priority than the
     // per-script font prefs when the script of the content is known.  This code
     // can possibly be removed later if users can easily access per-script font
     // prefs (e.g., via the extensions workflow), or the problem turns out to
     // not be really critical after all.
     if (browser_script != pref_script) {
       prefs->RegisterLocalizedStringPref(pref.pref_name,
                                          pref.resource_id,
                                          PrefService::UNSYNCABLE_PREF);
+      fonts_with_defaults.insert(pref.pref_name);
     }
   }
 
   // Register font prefs that don't have defaults.
-  RegisterFontFamilyMap(prefs, prefs::kWebKitStandardFontFamilyMap);
-  RegisterFontFamilyMap(prefs, prefs::kWebKitFixedFontFamilyMap);
-  RegisterFontFamilyMap(prefs, prefs::kWebKitSerifFontFamilyMap);
-  RegisterFontFamilyMap(prefs, prefs::kWebKitSansSerifFontFamilyMap);
-  RegisterFontFamilyMap(prefs, prefs::kWebKitCursiveFontFamilyMap);
-  RegisterFontFamilyMap(prefs, prefs::kWebKitFantasyFontFamilyMap);
-  RegisterFontFamilyMap(prefs, prefs::kWebKitPictographFontFamilyMap);
+  RegisterFontFamilyMap(prefs, prefs::kWebKitStandardFontFamilyMap,
+                        fonts_with_defaults);
+  RegisterFontFamilyMap(prefs, prefs::kWebKitFixedFontFamilyMap,
+                        fonts_with_defaults);
+  RegisterFontFamilyMap(prefs, prefs::kWebKitSerifFontFamilyMap,
+                        fonts_with_defaults);
+  RegisterFontFamilyMap(prefs, prefs::kWebKitSansSerifFontFamilyMap,
+                        fonts_with_defaults);
+  RegisterFontFamilyMap(prefs, prefs::kWebKitCursiveFontFamilyMap,
+                        fonts_with_defaults);
+  RegisterFontFamilyMap(prefs, prefs::kWebKitFantasyFontFamilyMap,
+                        fonts_with_defaults);
+  RegisterFontFamilyMap(prefs, prefs::kWebKitPictographFontFamilyMap,
+                        fonts_with_defaults);
 
   prefs->RegisterLocalizedIntegerPref(prefs::kWebKitDefaultFontSize,
                                       IDS_DEFAULT_FONT_SIZE,
                                       PrefService::UNSYNCABLE_PREF);
   prefs->RegisterLocalizedIntegerPref(prefs::kWebKitDefaultFixedFontSize,
                                       IDS_DEFAULT_FIXED_FONT_SIZE,
                                       PrefService::UNSYNCABLE_PREF);
   prefs->RegisterLocalizedIntegerPref(prefs::kWebKitMinimumFontSize,
                                       IDS_MINIMUM_FONT_SIZE,
                                       PrefService::UNSYNCABLE_PREF);
@@ skipping 54 matching lines @@
 
 void PrefsTabHelper::UpdateRendererPreferences() {
   renderer_preferences_util::UpdateFromSystemSettings(
       web_contents_->GetMutableRendererPrefs(), GetProfile());
   web_contents_->GetRenderViewHost()->SyncRendererPrefs();
 }
 
 Profile* PrefsTabHelper::GetProfile() {
   return Profile::FromBrowserContext(web_contents_->GetBrowserContext());
 }