Hide AXPlatformNode on ChromeOS.

ui/accessibility/platform/ax_platform_unique_id.cc

Index: ui/accessibility/platform/ax_platform_unique_id.cc
diff --git a/ui/accessibility/platform/ax_platform_unique_id.cc b/ui/accessibility/platform/ax_platform_unique_id.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ece23eb421e54f01c33d9bdb240ffc400b3f18cc
--- /dev/null
+++ b/ui/accessibility/platform/ax_platform_unique_id.cc
@@ -0,0 +1,20 @@
+// Copyright 2017 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 "ui/accessibility/platform/ax_platform_unique_id.h"
+
+namespace ui {
+
+int32_t GetNextAXPlatformNodeUniqueId() {
+  static int32_t next_unique_id = 1;
+  int32_t unique_id = next_unique_id;
+  if (next_unique_id == INT32_MAX)
+    next_unique_id = 1;
+  else
+    next_unique_id++;
+
+  return unique_id;
+}
+
+}  // namespace ui