Makes the tabstrip center the active tab when transitioning from

chrome/browser/ui/views/tabs/touch_tab_strip_layout.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/touch_tab_strip_layout.h"
 
 #include <stdio.h>
 
 #include "base/logging.h"
 #include "base/string_number_conversions.h"
@@ skipping 146 matching lines @@
 
 bool TouchTabStripLayout::IsStacked(int index) const {
   if (index == active_index() || tab_count() == mini_tab_count_ ||
       index < mini_tab_count_)
     return false;
   if (index > active_index())
     return ideal_x(index) != ideal_x(index - 1) + tab_offset();
   return ideal_x(index + 1) != ideal_x(index) + tab_offset();
 }
 
+void TouchTabStripLayout::SetActiveTabLocation(int x) {
+  if (!requires_stacking())
+    return;
+
+  const int index = active_index();
+  if (index <= mini_tab_count_)
+    return;
+
+  x = std::min(GetMaxX(index), std::max(x, GetMinX(index)));
+  if (x == ideal_x(index))
+    return;
+
+  SetIdealBoundsAt(index, x);
+  LayoutByTabOffsetBefore(index);
+  LayoutByTabOffsetAfter(index);
+}
+
 #if !defined(NDEBUG)
 std::string TouchTabStripLayout::BoundsString() const {
   std::string result;
   for (int i = 0; i < view_model_->view_size(); ++i) {
     if (!result.empty())
       result += " ";
     if (i == active_index())
       result += "[";
     result += base::IntToString(view_model_->ideal_bounds(i).x());
     if (i == active_index())
@@ skipping 257 matching lines @@
 }
 
 int TouchTabStripLayout::GetMinXCompressed(int index) const {
   DCHECK_GT(index, active_index());
   return std::max(
       width_ - width_for_count(tab_count() - index),
       ideal_x(active_index()) +
           stacked_padding_for_count(index - active_index()));
 
 }