Add ink drop ripple to overview mode button

ui/views/animation/ink_drop_impl.cc

Index: ui/views/animation/ink_drop_impl.cc
diff --git a/ui/views/animation/ink_drop_impl.cc b/ui/views/animation/ink_drop_impl.cc
index 0ec1aefd6149484a5282fd9309cbd50a28bf1733..9ee6ebb60f7d2ea77c97eb29d11f92823d92895a 100644
--- a/ui/views/animation/ink_drop_impl.cc
+++ b/ui/views/animation/ink_drop_impl.cc
@@ -707,6 +707,9 @@ void InkDropImpl::AnimationEnded(InkDropState ink_drop_state,
   highlight_state_->AnimationEnded(ink_drop_state, reason);
   if (reason != InkDropAnimationEndedReason::SUCCESS)
     return;
+  // |ink_drop_ripple_| might be null during destruction.
+  if (!ink_drop_ripple_)

[bruthig, 2016/11/11 17:30:40]

Can you add an InkDropImpl specific test for this?
Check out InkDropImplHideAutoHighlightTest.NoCrashDuringRippleTearDown.  You
will probably want to use the ZERO duration animation setting to force this use
case.

[mohsen, 2016/11/11 22:37:24]

Done.

+    return;
   if (ShouldAnimateToHidden(ink_drop_state)) {
     ink_drop_ripple_->AnimateToState(views::InkDropState::HIDDEN);
   } else if (ink_drop_state == views::InkDropState::HIDDEN) {