Added a views::test::TestInkDropAnimationObserverHelper

ui/views/animation/ink_drop_animation_observer.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 "ui/views/animation/ink_drop_animation_observer.h"
-
-#include <string>
-
-#include "base/logging.h"
-
-namespace views {
-
-std::string ToString(
-    InkDropAnimationObserver::InkDropAnimationEndedReason reason) {
-  switch (reason) {
-    case InkDropAnimationObserver::SUCCESS:
-      return std::string("SUCCESS");
-    case InkDropAnimationObserver::PRE_EMPTED:
-      return std::string("PRE_EMPTED");
-  }
-  NOTREACHED()
-      << "Should never be reached but is necessary for some compilers.";
-  return std::string();
-}
-
-}  // namespace views