Add support for branded strings into //components/strings.

Add two new files components_{chromium,google_chrome}_strings.grd into
stc/components and their empty .xtb files. Those files will hold branded
strings for the components (i.e. strings that reference the product,
see http://goo.gl/6614MQ).

Update repack steps to also pack those localizations too.

BUG=523362

Review URL: https://codereview.chromium.org/1307223005

Cr-Commit-Position: refs/heads/master@{#346891}
diff --git a/components/strings/components_chromium_strings_zh-CN.xtb b/components/strings/components_chromium_strings_zh-CN.xtb
new file mode 100644
index 0000000..fd85285
--- /dev/null
+++ b/components/strings/components_chromium_strings_zh-CN.xtb
@@ -0,0 +1,2 @@
+<?xml version="1.0" ?><!DOCTYPE translationbundle><translationbundle lang="zh-CN">
+</translationbundle>
\ No newline at end of file