Use GetDefaultLocaleListString for returning LocaleList

android_webview/browser/aw_content_browser_client.cc

Index: android_webview/browser/aw_content_browser_client.cc
diff --git a/android_webview/browser/aw_content_browser_client.cc b/android_webview/browser/aw_content_browser_client.cc
index 5f695eac250afdf2930dc842556e68bf3916387b..37f3701a8a6ca89d0d3a98e83e2f56eafffa20d5 100644
--- a/android_webview/browser/aw_content_browser_client.cc
+++ b/android_webview/browser/aw_content_browser_client.cc
@@ -158,17 +158,20 @@ AwLocaleManager* g_locale_manager = NULL;
 
 }  // anonymous namespace
 
+// TODO(yirui): could use similar logic as in
+//              PrependToAcceptLanguagesIfNecessary
+//              in chrome/browser/android/preferences/pref_service_bridge.cc
 // static
 std::string AwContentBrowserClient::GetAcceptLangsImpl() {

[Seigo Nonaka, 2016/11/15 05:15:59]

Question: Is there no unit tests for this function? If no, how about adding test
cases for making sure this change keeps existing behaviors.

[Yirui Huang, 2016/11/16 00:23:45]

Done.

-  // Start with the current locale.
-  std::string langs = g_locale_manager->GetLocale();
+  // Start with the current locale(s).
+  std::string locales_string = g_locale_manager->GetLocales();
 
-  // If we're not en-US, add in en-US which will be
+  // If accept languages do not contain en-US, add in en-US which will be
   // used with a lower q-value.
-  if (base::ToLowerASCII(langs) != "en-us") {
-    langs += ",en-US";
-  }
-  return langs;
+  size_t found_enUS = locales_string.find("en-US");

[Seigo Nonaka, 2016/11/15 05:15:59]

Question: do we no longer need to compare in case insensitively?

[Yirui Huang, 2016/11/16 00:23:45]

I thought locales_string that we got from here is from
LocaleUtils.getDefaultLocaleListString, which returns a well formed BCP47 form.
Added lower case checking just in case.

[Seigo Nonaka, 2016/11/16 01:26:14]

Please note that developer can set accept language manually in Android WebView.
Please see what happens when developer passes not well-formed BCP47 locale
string.

c.f.
http://stackoverflow.com/questions/12244375/how-can-i-override-android-webvie...

[Yirui Huang, 2016/11/16 01:49:12]

I see. Thanks for pointing this out. I wasn't aware of developer side.

+  if (found_enUS == std::string::npos)
+    locales_string += ",en-US";
+  return locales_string;
 }
 
 // static