CustomButton: restrict animation repaints to buttons that actually animate

ash/common/frame/caption_buttons/frame_caption_button.cc

 // Copyright 2013 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 "ash/common/frame/caption_buttons/frame_caption_button.h"
 
 #include "ui/gfx/animation/slide_animation.h"
 #include "ui/gfx/animation/throb_animation.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_palette.h"
@@ skipping 26 matching lines @@
 const char FrameCaptionButton::kViewClassName[] = "FrameCaptionButton";
 
 FrameCaptionButton::FrameCaptionButton(views::ButtonListener* listener,
                                        CaptionButtonIcon icon)
     : CustomButton(listener),
       icon_(icon),
       paint_as_active_(false),
       use_light_images_(false),
       alpha_(255),
       swap_images_animation_(new gfx::SlideAnimation(this)) {
+  set_animate_on_state_change(true);
   swap_images_animation_->Reset(1);
 
   // Do not flip the gfx::Canvas passed to the OnPaint() method. The snap left
   // and snap right button icons should not be flipped. The other icons are
   // horizontally symmetrical.
 }
 
 FrameCaptionButton::~FrameCaptionButton() {}
 
 void FrameCaptionButton::SetImage(CaptionButtonIcon icon,
@@ skipping 123 matching lines @@
     alpha *= inactive_alpha;
   }
 
   SkPaint paint;
   paint.setAlpha(alpha);
   canvas->DrawImageInt(to_center, (width() - to_center.width()) / 2,
                        (height() - to_center.height()) / 2, paint);
 }
 
 }  // namespace ash