Allows a single tab to be draggable from a maximized browser on ash.

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 1126 matching lines @@
       ((event.type() == ui::ET_MOUSE_PRESSED &&
         (((event.flags() & ui::EF_FROM_TOUCH) &&
           static_cast<const ui::MouseEvent&>(event).IsLeftMouseButton()) ||
          (!(event.flags() & ui::EF_FROM_TOUCH) &&
           static_cast<const ui::MouseEvent&>(event).IsControlDown()))) ||
        (event.type() == ui::ET_GESTURE_BEGIN && !event.IsControlDown()))) {
     move_behavior = TabDragController::MOVE_VISIBILE_TABS;
   }
 
   views::Widget* widget = GetWidget();
-
-  // Don't allow detaching from maximized or fullscreen windows (in ash) when
-  // all the tabs are selected and there is only one display. Since the window
-  // is maximized or fullscreen, we know there are no other tabbed browsers the
-  // user can drag to.
-  const chrome::HostDesktopType host_desktop_type =
-      chrome::GetHostDesktopTypeForNativeView(widget->GetNativeView());
-  if (host_desktop_type == chrome::HOST_DESKTOP_TYPE_ASH &&
-      (widget->IsMaximized() || widget->IsFullscreen()) &&
-      static_cast<int>(tabs.size()) == tab_count() &&
-      gfx::Screen::GetScreenFor(widget->GetNativeView())->GetNumDisplays() == 1)
-    detach_behavior = TabDragController::NOT_DETACHABLE;
-
 #if defined(OS_WIN)
   // It doesn't make sense to drag tabs out on Win8's single window Metro mode.
   if (win8::IsSingleWindowMetroMode())
     detach_behavior = TabDragController::NOT_DETACHABLE;
 #endif
   // Gestures don't automatically do a capture. We don't allow multiple drags at
   // the same time, so we explicitly capture.
   if (event.type() == ui::ET_GESTURE_BEGIN)
     widget->SetCapture(this);
   drag_controller_.reset(new TabDragController);
@@ skipping 1586 matching lines @@
 #if defined(USE_AURA)
   return chrome::GetHostDesktopTypeForNativeView(
       GetWidget()->GetNativeView()) == chrome::HOST_DESKTOP_TYPE_ASH;
 #else
   if (ui::GetDisplayLayout() != ui::LAYOUT_TOUCH)
     return false;
 #endif
 
   return true;
 }