[Smart Lock] Add a private API to show an error bubble anchored to the Smart Lock app window.

chrome/browser/ui/proximity_auth/proximity_auth_error_bubble.cc

+// Copyright 2015 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 "chrome/browser/ui/proximity_auth/proximity_auth_error_bubble.h"
+
+#include "base/logging.h"
+
+#if !defined(TOOLKIT_VIEWS)
+void ShowProximityAuthErrorBubble(const base::string16& message,
+                                  const gfx::Range& link_range,
+                                  const GURL& link_url,
+                                  const gfx::Rect& anchor_rect,
+                                  content::WebContents* web_contents) {
+  NOTIMPLEMENTED();
+}
+#endif