Browser: add to customize and show useragent

Add for carrier feature which requires to use useragent with
specified format. We try to load carrier useragent if needed
and show useragent in "about" menu item.

CRs-Fixed: 516733

Change-Id: Ifae25644d9ad5387684e3ff1e691e20db9a45e2a
diff --git a/res/menu/browser.xml b/res/menu/browser.xml
index 9be1208..9578026 100644
--- a/res/menu/browser.xml
+++ b/res/menu/browser.xml
@@ -104,6 +104,9 @@
         <item
             android:id="@+id/exit_menu_id"
             android:title="@string/exit" />
+        <item
+            android:id="@+id/about_menu_id"
+            android:title="@string/about" />
         <!-- followings are debug only -->
         <item
             android:id="@+id/dump_nav_menu_id"