Enhanced the InkDropRippleImpl to create/destroy InkDropAnimations as needed.

ui/views/animation/ink_drop_state.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_state.h"
+
+#include <iostream>
+#include <string>
+
+#include "base/logging.h"
+
+namespace views {
+
+std::string ToString(InkDropState state) {
+  switch (state) {
+    case InkDropState::HIDDEN:
+      return std::string("HIDDEN");
+    case InkDropState::ACTION_PENDING:
+      return std::string("ACTION_PENDING");
+    case InkDropState::QUICK_ACTION:
+      return std::string("QUICK_ACTION");
+    case InkDropState::SLOW_ACTION_PENDING:
+      return std::string("SLOW_ACTION_PENDING");
+    case InkDropState::SLOW_ACTION:
+      return std::string("SLOW_ACTION");
+    case InkDropState::ACTIVATED:
+      return std::string("ACTIVATED");
+    case InkDropState::DEACTIVATED:
+      return std::string("DEACTIVATED");
+  }
+  NOTREACHED()
+      << "Should never be reached but is necessary for some compilers.";
+  return std::string("UNKNOWN");
+}
+
+}  // namespace views