CustomButton: restrict animation repaints to buttons that actually animate

ui/views/controls/button/image_button.cc

 // Copyright (c) 2012 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 "ui/views/controls/button/image_button.h"
 
 #include <utility>
 
 #include "base/strings/utf_string_conversions.h"
 #include "ui/accessibility/ax_view_state.h"
@@ skipping 30 matching lines @@
 }
 
 ImageButton::~ImageButton() {
 }
 
 const gfx::ImageSkia& ImageButton::GetImage(ButtonState state) const {
   return images_[state];
 }
 
 void ImageButton::SetImage(ButtonState for_state, const gfx::ImageSkia* image) {
+  if (for_state == STATE_HOVERED)
+    set_animate_on_state_change(image != nullptr);
   images_[for_state] = image ? *image : gfx::ImageSkia();
   PreferredSizeChanged();
   if (state() == for_state)
     SchedulePaint();
 }
 
 void ImageButton::SetBackground(SkColor color,
                                 const gfx::ImageSkia* image,
                                 const gfx::ImageSkia* mask) {
   if (image == NULL || mask == NULL) {
@@ skipping 214 matching lines @@
   // accessible toggle button.
   if ((toggled_ && !images_[ButtonState::STATE_NORMAL].isNull()) ||
       (!toggled_ && !alternate_images_[ButtonState::STATE_NORMAL].isNull())) {
     state->role = ui::AX_ROLE_TOGGLE_BUTTON;
     if (toggled_)
       state->AddStateFlag(ui::AX_STATE_PRESSED);
   }
 }
 
 }  // namespace views