Clip tabs in overflow mode.

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 "ash/accelerators/accelerator_commands.h"
@@ skipping 1299 matching lines @@
     }
   } else {
     index = GetInsertionIndexFrom(dragged_bounds, 0);
   }
   if (index == -1) {
     const int last_tab_right =
         attached_tabstrip_->ideal_bounds(tab_count - 1).right();
     index = (dragged_bounds.right() > last_tab_right) ? tab_count : 0;
   }
 
-  if (!drag_data_[0].attached_tab) {
-    // If 'attached_tab' is NULL, it means we're in the process of attaching and
-    // don't need to constrain the index.
-    return index;
+  int last_insertion_point = attached_tabstrip_->GetModelIndexOfTab(
+      attached_tabstrip_->GetLastVisibleTab()) + 1;
+  if (drag_data_[0].attached_tab) {
+    // We're not in the process of attaching, so clamp the insertion point to
+    // keep it within the visible region.
+    last_insertion_point = std::max(
+        0, last_insertion_point - static_cast<int>(drag_data_.size()));
   }
 
-  int max_index = GetModel(attached_tabstrip_)->count() -
-      static_cast<int>(drag_data_.size());
-  return std::max(0, std::min(max_index, index));
+  // Ensure the first dragged tab always stays in the visible index range.
+  return std::min(index, last_insertion_point);
 }
 
 bool TabDragController::ShouldDragToNextStackedTab(
     const gfx::Rect& dragged_bounds,
     int index) const {
   if (index + 1 >= attached_tabstrip_->tab_count() ||
       !attached_tabstrip_->touch_layout_->IsStacked(index + 1) ||
       (mouse_move_direction_ & kMovedMouseRight) == 0)
     return false;
 
@@ skipping 608 matching lines @@
        it != browser_list->end(); ++it) {
     if ((*it)->tab_strip_model()->empty())
       exclude.insert((*it)->window()->GetNativeWindow());
   }
 #endif
   return GetLocalProcessWindowAtPoint(host_desktop_type_,
                                       screen_point,
                                       exclude);
 
 }