Extend the custom Jump List API

Add `app.getJumpListSettings()` and `app.setJumpList(callback)` that
make it possible to fully customize the Jump List of an Electron app.
It is now possible to:
- Add tasks to the standard `Tasks` category.
- Add separators to the standard `Tasks` category.
- Add custom categories containing tasks and file links.
- Add system managed Recent/Frequent categories.
- Remove the custom Jump List.

atom/browser/api/atom_api_app.h

@@ -26,10 +26,14 @@ class FilePath;
 
 namespace mate {
 class Arguments;
-}
+}  // namespace mate
 
 namespace atom {
 
+#if defined(OS_WIN)
+enum class JumpListResult : int;
+#endif
+
 namespace api {
 
 class App : public AtomBrowserClient::Delegate,
@@ -120,6 +124,14 @@ class App : public AtomBrowserClient::Delegate,
                          const net::CompletionCallback& callback);
 #endif
 
+#if defined(OS_WIN)
+  // Get the current Jump List settings.
+  v8::Local<v8::Value> GetJumpListSettings();
+
+  // Set or remove a custom Jump List for the application.
+  JumpListResult SetJumpList(v8::Local<v8::Value> val, mate::Arguments* args);
+#endif  // defined(OS_WIN)
+
   std::unique_ptr<ProcessSingleton> process_singleton_;
 
 #if defined(USE_NSS_CERTS)