Makes the tabstrip center the active tab when transitioning from

chrome/browser/ui/views/tabs/tab_strip.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_strip.h"
 
 #if defined(OS_WIN)
 #include <windowsx.h>
 #endif
 
@@ skipping 600 matching lines @@
   // so that if they call back we aren't in a weird state.
   RemoveAllChildViews(true);
 }
 
 void TabStrip::SetLayoutType(TabStripLayoutType layout_type,
                              bool adjust_layout) {
   adjust_layout_ = adjust_layout;
   if (layout_type == layout_type_)
     return;
 
+  const int active_index = controller_->GetActiveIndex();
+  int active_center = 0;
+  if (active_index != -1) {
+    active_center = ideal_bounds(active_index).x() +
+        ideal_bounds(active_index).width() / 2;
+  }
   layout_type_ = layout_type;
   SetResetToShrinkOnExit(false);
   SwapLayoutIfNecessary();
+  // When transitioning to stacked try to keep the active tab centered.
+  if (touch_layout_.get() && active_index != -1) {
+    touch_layout_->SetActiveTabLocation(
+        active_center - ideal_bounds(active_index).width() / 2);
+    AnimateToIdealBounds();
+  }
 }
 
 gfx::Rect TabStrip::GetNewTabButtonBounds() {
   return newtab_button_->bounds();
 }
 
 bool TabStrip::SizeTabButtonToTopOfTabStrip() {
   return browser_defaults::kSizeTabButtonToTopOfTabStrip ||
       (GetWidget() && GetWidget()->IsMaximized());
 }
@@ skipping 1787 matching lines @@
   if (!adjust_layout_)
     return false;
 
 #if !defined(OS_CHROMEOS)
   if (ui::GetDisplayLayout() != ui::LAYOUT_TOUCH)
     return false;
 #endif
 
   return true;
 }