Optimize RTL check in ICU to avoid mmap access.

base/i18n/rtl.h

 // Copyright (c) 2011 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 BASE_I18N_RTL_H_
 #define BASE_I18N_RTL_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 43 matching lines @@
 // Returns true if the application text direction is right-to-left.
 BASE_I18N_EXPORT bool IsRTL();
 
 // Returns whether the text direction for the default ICU locale is RTL.  This
 // assumes that SetICUDefaultLocale has been called to set the default locale to
 // the UI locale of Chrome.
 // NOTE: Generally, you should call IsRTL() instead of this.
 BASE_I18N_EXPORT bool ICUIsRTL();
 
 // Returns the text direction for |locale_name|.
+// As a startup optimization, this method checks the locale against a list of
+// Chrome-supported RTL locales.
+BASE_I18N_EXPORT TextDirection
+GetTextDirectionForLocaleInStartUp(const char* locale_name);
+
+// Returns the text direction for |locale_name|.
 BASE_I18N_EXPORT TextDirection GetTextDirectionForLocale(
     const char* locale_name);
 
 // Given the string in |text|, returns the directionality of the first or last
 // character with strong directionality in the string. If no character in the
 // text has strong directionality, LEFT_TO_RIGHT is returned. The Bidi
 // character types L, LRE, LRO, R, AL, RLE, and RLO are considered as strong
 // directionality characters. Please refer to http://unicode.org/reports/tr9/
 // for more information.
 BASE_I18N_EXPORT TextDirection GetFirstStrongCharacterDirection(
@@ skipping 66 matching lines @@
 // return the text itself. Explicit bidi control characters display and have
 // semantic effect. They can be deleted so they might not always appear in a
 // pair.
 BASE_I18N_EXPORT string16 StripWrappingBidiControlCharacters(
     const string16& text) WARN_UNUSED_RESULT;
 
 }  // namespace i18n
 }  // namespace base
 
 #endif  // BASE_I18N_RTL_H_