Adds locale strings to Chromecast build.

chromecast/shell/browser/cast_http_user_agent_settings.cc

Index: chromecast/shell/browser/cast_http_user_agent_settings.cc
diff --git a/chromecast/shell/browser/cast_http_user_agent_settings.cc b/chromecast/shell/browser/cast_http_user_agent_settings.cc
index 32957a6247d0b7ae38153ee77c6596cf0edf90d1..fbc43b3916f2dced26ce42a37b68949e9fdffa86 100644
--- a/chromecast/shell/browser/cast_http_user_agent_settings.cc
+++ b/chromecast/shell/browser/cast_http_user_agent_settings.cc
@@ -7,7 +7,9 @@
 #include "base/logging.h"
 #include "chromecast/shell/common/cast_content_client.h"
 #include "content/public/browser/browser_thread.h"
+#include "grit/chromecast_settings.h"
 #include "net/http/http_util.h"
+#include "ui/base/l10n/l10n_util.h"
 
 namespace chromecast {
 namespace shell {
@@ -21,7 +23,11 @@ CastHttpUserAgentSettings::~CastHttpUserAgentSettings() {
 }
 
 std::string CastHttpUserAgentSettings::GetAcceptLanguage() const {
-  accept_language_ = net::HttpUtil::GenerateAcceptLanguageHeader("en-US");
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+  if (accept_language_.empty()) {
+    accept_language_ = net::HttpUtil::GenerateAcceptLanguageHeader(
+        l10n_util::GetStringUTF8(IDS_CHROMECAST_SETTINGS_ACCEPT_LANGUAGES));
+  }
   return accept_language_;
 }