Adding ripple effect for clicks on MD slider

ui/views/controls/slider.cc

Index: ui/views/controls/slider.cc
diff --git a/ui/views/controls/slider.cc b/ui/views/controls/slider.cc
index dd1148ff1a59123e6f2c960404aee5ffe732267c..d390792c52db17ec139b19d053af5d20049e8fea 100644
--- a/ui/views/controls/slider.cc
+++ b/ui/views/controls/slider.cc
@@ -179,6 +179,7 @@ float Slider::GetAnimatingValue() const{
 bool Slider::OnMousePressed(const ui::MouseEvent& event) {
   if (!event.IsOnlyLeftMouseButton())
     return false;
+  SetFocus(true);

[bruthig, 2016/09/21 00:27:46]

Instead of calling SetFocus() from OnMousePressed(), OnMouseReleased(),
OnGestureEvent(), I think you should move it to OnSliderDragStarted() and
OnSliderDragEnded().

[yiyix, 2016/09/21 15:20:52]

good call!!

   OnSliderDragStarted();
   PrepareForMove(event.location().x());
   MoveButtonTo(event.location());
@@ -191,6 +192,7 @@ bool Slider::OnMouseDragged(const ui::MouseEvent& event) {
 }
 
 void Slider::OnMouseReleased(const ui::MouseEvent& event) {
+  SetFocus(false);
   OnSliderDragEnded();
 }
 
@@ -208,11 +210,13 @@ bool Slider::OnKeyPressed(const ui::KeyEvent& event) {
 
 void Slider::OnFocus() {
   View::OnFocus();
+  SetFocus(true);
   SchedulePaint();
 }
 
 void Slider::OnBlur() {
   View::OnBlur();
+  SetFocus(false);
   SchedulePaint();
 }
 
@@ -226,10 +230,12 @@ void Slider::OnGestureEvent(ui::GestureEvent* event) {
       // Intentional fall through to next case.
     case ui::ET_GESTURE_SCROLL_BEGIN:
     case ui::ET_GESTURE_SCROLL_UPDATE:
+      SetFocus(true);
       MoveButtonTo(event->location());
       event->SetHandled();
       break;
     case ui::ET_GESTURE_END:
+      SetFocus(false);
       MoveButtonTo(event->location());
       event->SetHandled();
       if (event->details().touch_points() <= 1)