Reland change for aura tooltips that was revert due to build break:

ui/views/test/test_tooltip_client.h

+// Copyright (c) 2011 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.
+
+#ifndef UI_AURA_TEST_TEST_TOOLTIP_CLIENT_H_
+#define UI_AURA_TEST_TEST_TOOLTIP_CLIENT_H_
+#pragma once
+
+#include "base/compiler_specific.h"
+#include "ui/aura/client/tooltip_client.h"
+
+namespace aura {
+class Window;
+
+namespace test {
+
+class TestTooltipClient : public TooltipClient {
+ public:
+  TestTooltipClient();
+  virtual ~TestTooltipClient();
+
+ private:
+  // Overridden from TooltipClient:
+  virtual void UpdateTooltip(Window* target) OVERRIDE {}
+
+  DISALLOW_COPY_AND_ASSIGN(TestTooltipClient);
+};
+
+}  // namespace test
+}  // namespace aura
+
+#endif  // UI_AURA_TEST_TEST_TOOLTIP_CLIENT_H_