Re-enable PRESUBMIT check for empty unique_ptr<> rvalue

ui/events/blink/input_handler_proxy_unittest.cc

 // Copyright 2013 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/events/blink/input_handler_proxy.h"
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/test/histogram_tester.h"
@@ skipping 102 matching lines @@
                             const gfx::Vector2dF& scroll_delta));
   MOCK_METHOD1(ScrollBy, cc::InputHandlerScrollResult(cc::ScrollState*));
   MOCK_METHOD2(ScrollVerticallyByPage,
                bool(const gfx::Point& viewport_point,
                     cc::ScrollDirection direction));
   MOCK_METHOD1(ScrollEnd, void(cc::ScrollState*));
   MOCK_METHOD0(FlingScrollBegin, cc::InputHandler::ScrollStatus());
 
   std::unique_ptr<cc::SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
       ui::LatencyInfo* latency) override {
-    return std::unique_ptr<cc::SwapPromiseMonitor>();
+    return nullptr;
   }
 
   cc::ScrollElasticityHelper* CreateScrollElasticityHelper() override {
     return NULL;
   }
   bool GetScrollOffsetForLayer(int layer_id,
                                gfx::ScrollOffset* offset) override {
     return false;
   }
   bool ScrollLayerTo(int layer_id, const gfx::ScrollOffset& offset) override {
@@ skipping 2667 matching lines @@
       testing::ElementsAre(base::Bucket(1, 1), base::Bucket(3, 1),
                            base::Bucket(5, 1), base::Bucket(14, 1)));
 }
 
 
 INSTANTIATE_TEST_CASE_P(AnimateInput,
                         InputHandlerProxyTest,
                         testing::ValuesIn(test_types));
 }  // namespace test
 }  // namespace ui