app_shell: Add experimental shellPrivate extension API

extensions/browser/api/shell_private/shell_private_api.cc

Index: extensions/browser/api/shell_private/shell_private_api.cc
diff --git a/extensions/browser/api/shell_private/shell_private_api.cc b/extensions/browser/api/shell_private/shell_private_api.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e0313ff1dc1333ab767899376158b80dbae5c431
--- /dev/null
+++ b/extensions/browser/api/shell_private/shell_private_api.cc
@@ -0,0 +1,21 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "extensions/browser/api/shell_private/shell_private_api.h"
+
+namespace extensions {
+
+ShellPrivatePrintHelloFunction::ShellPrivatePrintHelloFunction() {
+}
+
+ShellPrivatePrintHelloFunction::~ShellPrivatePrintHelloFunction() {
+}
+
+ExtensionFunction::ResponseAction ShellPrivatePrintHelloFunction::Run() {
+  // Warning so it shows in Release and avoids presubmit check for INFO.
+  LOG(WARNING) << "hello";
+  return RespondNow(NoArguments());
+}
+
+}  // namespace extensions