Added a views::test::TestInkDropAnimationObserverHelper

ui/views/animation/ink_drop_animation_ended_reason.cc

+// Copyright 2016 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_ended_reason.h"
+
+#include "base/logging.h"
+
+namespace views {
+
+std::string ToString(InkDropAnimationEndedReason reason) {
+  switch (reason) {
+    case InkDropAnimationEndedReason::SUCCESS:
+      return "SUCCESS";
+    case InkDropAnimationEndedReason::PRE_EMPTED:
+      return "PRE_EMPTED";
+  }
+  NOTREACHED()
+      << "Should never be reached but is necessary for some compilers.";
+  return std::string();
+}
+
+}  // namespace views