Experiment to hide close buttons of inactive tabs when using touch

chrome/browser/ui/views/tabs/tab.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 "chrome/browser/ui/views/tabs/tab.h"
 
 #include <limits>
 
 #include "base/command_line.h"
 #include "base/debug/alias.h"
@@ skipping 1426 matching lines @@
 }
 
 bool Tab::ShouldShowMediaIndicator() const {
   return chrome::ShouldTabShowMediaIndicator(
       IconCapacity(), data().mini, IsActive(), data().show_icon,
       media_indicator_button_ ? media_indicator_button_->showing_media_state() :
                                 data_.media_state);
 }
 
 bool Tab::ShouldShowCloseBox() const {
+  if (!IsActive() && controller_->ShouldHideCloseButtonForInactiveTab(this))
+    return false;
+
   return chrome::ShouldTabShowCloseButton(
       IconCapacity(), data().mini, IsActive());
 }
 
 double Tab::GetThrobValue() {
   const bool is_selected = IsSelected();
   const double min = is_selected ? kSelectedTabOpacity : 0;
   const double scale = is_selected ? kSelectedTabThrobScale : 1;
 
   // Showing both the pulse and title change animation at the same time is too
@@ skipping 142 matching lines @@
                          const gfx::ImageSkia& image) {
   DCHECK_NE(scale_factor, ui::SCALE_FACTOR_NONE);
   ImageCacheEntry entry;
   entry.resource_id = resource_id;
   entry.scale_factor = scale_factor;
   entry.image = image;
   image_cache_->push_front(entry);
   if (image_cache_->size() > kMaxImageCacheSize)
     image_cache_->pop_back();
 }