Fixes couple of bugs in the TabStrip that could cause tabs to dance

chrome/browser/ui/views/tabs/tab_drag_controller.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_drag_controller.h"
 
 #include <math.h>
 #include <set>
 
 #include "base/auto_reset.h"
@@ skipping 346 matching lines @@
 
 // static
 const int TabDragController::kVerticalDetachMagnetism = 15;
 
 TabDragController::TabDragController()
     : detach_into_browser_(ShouldDetachIntoNewBrowser()),
       source_tabstrip_(NULL),
       attached_tabstrip_(NULL),
       screen_(NULL),
       host_desktop_type_(chrome::HOST_DESKTOP_TYPE_NATIVE),
-      source_tab_offset_(0),
       offset_to_width_ratio_(0),
       old_focused_view_(NULL),
       last_move_screen_loc_(0),
       started_drag_(false),
       active_(true),
       source_tab_index_(std::numeric_limits<size_t>::max()),
       initial_move_(true),
       detach_behavior_(DETACHABLE),
       move_behavior_(REORDER),
       mouse_move_direction_(0),
@@ skipping 46 matching lines @@
     const ui::ListSelectionModel& initial_selection_model,
     DetachBehavior detach_behavior,
     MoveBehavior move_behavior) {
   DCHECK(!tabs.empty());
   DCHECK(std::find(tabs.begin(), tabs.end(), source_tab) != tabs.end());
   source_tabstrip_ = source_tabstrip;
   screen_ = gfx::Screen::GetScreenFor(
       source_tabstrip->GetWidget()->GetNativeView());
   host_desktop_type_ = chrome::GetHostDesktopTypeForNativeView(
       source_tabstrip->GetWidget()->GetNativeView());
-  source_tab_offset_ = source_tab_offset;
   start_point_in_screen_ = gfx::Point(source_tab_offset, mouse_offset.y());
   views::View::ConvertPointToScreen(source_tab, &start_point_in_screen_);
   mouse_offset_ = mouse_offset;
   detach_behavior_ = detach_behavior;
   move_behavior_ = move_behavior;
   last_point_in_screen_ = start_point_in_screen_;
   last_move_screen_loc_ = start_point_in_screen_.x();
   initial_tab_positions_ = source_tabstrip->GetTabXCoordinates();
   if (detach_into_browser_)
     GetModel(source_tabstrip_)->AddObserver(this);
 
   drag_data_.resize(tabs.size());
   for (size_t i = 0; i < tabs.size(); ++i)
     InitTabDragData(tabs[i], &(drag_data_[i]));
   source_tab_index_ =
       std::find(tabs.begin(), tabs.end(), source_tab) - tabs.begin();
 
   // Listen for Esc key presses.
   MessageLoopForUI::current()->AddObserver(this);
 
   if (source_tab->width() > 0) {
-    offset_to_width_ratio_ = static_cast<float>(source_tab_offset_) /
+    offset_to_width_ratio_ = static_cast<float>(
+        source_tab->GetMirroredXInView(source_tab_offset)) /
         static_cast<float>(source_tab->width());
   }
   InitWindowCreatePoint();
   initial_selection_model_.Copy(initial_selection_model);
 }
 
 // static
 bool TabDragController::IsAttachedTo(TabStrip* tab_strip) {
   return (instance_ && instance_->active() &&
           instance_->attached_tabstrip() == tab_strip);
@@ skipping 1575 matching lines @@
 gfx::Vector2d TabDragController::GetWindowOffset(
     const gfx::Point& point_in_screen) {
   TabStrip* owning_tabstrip = (attached_tabstrip_ && detach_into_browser_) ?
       attached_tabstrip_ : source_tabstrip_;
   views::View* toplevel_view = owning_tabstrip->GetWidget()->GetContentsView();
 
   gfx::Point point = point_in_screen;
   views::View::ConvertPointFromScreen(toplevel_view, &point);
   return point.OffsetFromOrigin();
 }