Add context menu support (issue #509):

- Add new CefContextMenuHandler, CefContextMenuParams and CefMenuModel classes.
- Add cef_strings.grd and related infrastructure for supporting translation of CEF strings.
- Generate include/cef_pack_resources.h and include/cef_pack_strings.h files at build time that include all IDs used by CEF pack files.

git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@595 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

include/capi/cef_client_capi.h

@@ -92,6 +92,13 @@ typedef struct _cef_client_t {
   struct _cef_jsdialog_handler_t* (CEF_CALLBACK *get_jsdialog_handler)(
       struct _cef_client_t* self);
 
+  ///
+  // Return the handler for context menus. If no handler is provided the default
+  // implementation will be used.
+  ///
+  struct _cef_context_menu_handler_t* (CEF_CALLBACK *get_context_menu_handler)(
+      struct _cef_client_t* self);
+
   ///
   // Called when a new message is received from a different process. Return true
   // (1) if the message was handled or false (0) otherwise. Do not keep a