[i18n] escape commas, polymer workaround

ui/base/template_expressions.cc

Index: ui/base/template_expressions.cc
diff --git a/ui/base/template_expressions.cc b/ui/base/template_expressions.cc
index c8d49a95f86e55bc3e31e79974367116f413dee6..14b638edb2415de73551d5f7e54f76b856ef7cf3 100644
--- a/ui/base/template_expressions.cc
+++ b/ui/base/template_expressions.cc
@@ -31,6 +31,9 @@ std::string BackslashEscape(const std::string& in_string) {
       case '"':
         out.append("\\\"");
         break;
+      case ',':
+        out.append("\\,");

[dpapad, 2017/04/14 01:03:20]

FYI, escaping the commas seems to be expected by Polymer, even though not
documented anywhere (or anywhere I could find), see test case at
https://github.com/Polymer/polymer/blob/9997a049ef092c55d324881892f850f6154e3....

+        break;
       default:
         out += c;
     }