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..f845a4a8b85881e6cbc0183c455c76e0720a53f3 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.

[jungshik at Google, 2015/08/11 19:23:13]

Please, make it even clearer that this is only for the start-up and
GetTextDirectionForLocale() is the one to use otherwise. 

+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);