Optimize RTL check in ICU to avoid mmap access.

base/i18n/rtl.h

Index: base/i18n/rtl.h
diff --git a/base/i18n/rtl.h b/base/i18n/rtl.h
index 9b9a0dcd31cdf4468a8150897a81ea6d0c9fe60d..bba93ce8f56d2bc8d7161a081eabaf7779dfda3a 100644
--- a/base/i18n/rtl.h
+++ b/base/i18n/rtl.h
@@ -61,6 +61,12 @@ BASE_I18N_EXPORT bool IsRTL();
 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);