MD Buttons: Don't add layers for hidden -> hidden transitions.

ui/views/animation/ink_drop_impl_unittest.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_impl.h"
 
 #include "base/macros.h"
 #include "base/test/test_simple_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 352 matching lines @@
   test_api_.CompleteAnimations();
   EXPECT_EQ(0, ink_drop_host_.num_ink_drop_layers());
 
   ink_drop_.SnapToActivated();
   EXPECT_EQ(1, ink_drop_host_.num_ink_drop_layers());
   ink_drop_.SetHovered(true);
   EXPECT_EQ(1, ink_drop_host_.num_ink_drop_layers());
   EXPECT_TRUE(test_api_.IsHighlightFadingInOrVisible());
 }
 
+// Test that (re-)hiding or un-hovering a hidden ink drop doesn't add layers.
+TEST_F(InkDropImplTest, AlwaysHiddenInkDropHasNoLayers) {
+  ink_drop_host_.set_should_show_highlight(true);
+
+  EXPECT_EQ(0, ink_drop_host_.num_ink_drop_layers_added());
+
+  ink_drop_.AnimateToState(InkDropState::HIDDEN);
+  EXPECT_EQ(0, ink_drop_host_.num_ink_drop_layers_added());
+
+  ink_drop_.SetHovered(false);
+  EXPECT_EQ(0, ink_drop_host_.num_ink_drop_layers_added());
+}
+
 }  // namespace views