[ash-md] Animates ToggleButton highlight to move it in sync with the thumb

ui/views/controls/button/toggle_button.cc

Index: ui/views/controls/button/toggle_button.cc
diff --git a/ui/views/controls/button/toggle_button.cc b/ui/views/controls/button/toggle_button.cc
index 30bf562a54887ce6a3b62c24af0408b80104c884..e382b4083e7c7b0b196b181f516c3224755f297b 100644
--- a/ui/views/controls/button/toggle_button.cc
+++ b/ui/views/controls/button/toggle_button.cc
@@ -99,6 +99,9 @@ void ToggleButton::OnPaint(gfx::Canvas* canvas) {
       color_utils::AlphaBlend(thumb_on_color, thumb_off_color, blend));
   canvas->DrawCircle(gfx::RectF(thumb_bounds).CenterPoint(),
                      thumb_bounds.height() / 2.f, thumb_paint);
+
+  // Adjust thumb ink drop highlight position to make it animate with the thumb.
+  OffsetInkDropRipple(thumb_bounds.CenterPoint() - original_center_point_);

[Evan Stade, 2016/10/10 17:33:15]

I'm kind of skeptical this will look great/stay in sync at a per-frame level. I
think instead we should have the thumb be a separate View and AddInkDropLayer
makes the ink drop layer a child of that view's layer.

[varkha, 2016/10/12 00:44:59]

Done.

 }
 
 void ToggleButton::NotifyClick(const ui::Event& event) {
@@ -110,6 +113,11 @@ void ToggleButton::OnNativeThemeChanged(const ui::NativeTheme* theme) {
   SchedulePaint();
 }
 
+void ToggleButton::AddInkDropLayer(ui::Layer* ink_drop_layer) {
+  original_center_point_ = GetThumbBounds().CenterPoint();
+  CustomButton::AddInkDropLayer(ink_drop_layer);
+}
+
 std::unique_ptr<InkDropRipple> ToggleButton::CreateInkDropRipple() const {
   return CreateDefaultInkDropRipple(GetThumbBounds().CenterPoint());
 }