CustomButton cleanup: make protected members private, create accessors

mash/wm/frame/caption_buttons/frame_caption_button.cc

Index: mash/wm/frame/caption_buttons/frame_caption_button.cc
diff --git a/mash/wm/frame/caption_buttons/frame_caption_button.cc b/mash/wm/frame/caption_buttons/frame_caption_button.cc
index ca1501fb082e74b86ec44fadc29d59d1ae92283e..491829fe582a10609eeac4613b507e1db839b781 100644
--- a/mash/wm/frame/caption_buttons/frame_caption_button.cc
+++ b/mash/wm/frame/caption_buttons/frame_caption_button.cc
@@ -111,11 +111,9 @@ const char* FrameCaptionButton::GetClassName() const {
 }
 
 void FrameCaptionButton::OnPaint(gfx::Canvas* canvas) {
-  if (hover_animation_->is_animating() || state() == STATE_HOVERED) {
+  if (hover_animation().is_animating() || state() == STATE_HOVERED) {
     int hovered_background_alpha =
-        hover_animation_->is_animating()
-            ? hover_animation_->CurrentValueBetween(0, 255)
-            : 255;
+        hover_animation().CurrentValueBetween(0, 255);
     SkPaint paint;
     paint.setAlpha(hovered_background_alpha);
     canvas->DrawImageInt(hovered_background_image_, 0, 0, paint);
@@ -176,9 +174,9 @@ void FrameCaptionButton::PaintCentered(gfx::Canvas* canvas,
   if (!paint_as_active_) {
     // Paint icons as active when they are hovered over or pressed.
     double inactive_alpha = kInactiveIconAlpha;
-    if (hover_animation_->is_animating()) {
+    if (hover_animation().is_animating()) {
       inactive_alpha =
-          hover_animation_->CurrentValueBetween(inactive_alpha, 1.0f);
+          hover_animation().CurrentValueBetween(inactive_alpha, 1.0f);
     } else if (state() == STATE_PRESSED || state() == STATE_HOVERED) {
       inactive_alpha = 1.0f;
     }