Removes grab input window and extra grab and ungrab in X11WholeScreenMoveLoop

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 1161 matching lines @@
   dragged_widget->SetVisibilityChangedAnimationsEnabled(false);
   Attach(dragged_browser_view->tabstrip(), gfx::Point());
   AdjustBrowserAndTabBoundsForDrag(last_tabstrip_width,
                                    point_in_screen,
                                    &drag_bounds);
   WindowPositionManagedUpdater updater;
   dragged_widget->AddObserver(&updater);
   browser->window()->Show();
   dragged_widget->RemoveObserver(&updater);
   dragged_widget->SetVisibilityChangedAnimationsEnabled(true);
+  // Set capture after the newly created browser widget is visible.
+  attached_tabstrip_->GetWidget()->SetCapture(attached_tabstrip_);

[sky, 2014/05/27 13:27:04]

Couple of questions. Why is this needed here since Attach should set capture?
Since this seems X11 specific, can it be moved to
DesktopWindowTreeHostX11::RunMoveLoop?

[varkha, 2014/05/28 19:11:46]

I had this comment here before, but it is higher up the review chain:
This makes sure that capture is really where we think it is after calling
Attach(). Attach() would normally set capture on attached widget but with Aura
fails to do so because of IsVisible() check in Window::SetCapture(). This was
wrong before but worked because of additional capture in X11WholeScreenMoveLoop.
Simplifying X11WholeScreenMoveLoop exposed this.
It worked on other Aura platforms because NativeWidgetAura::RunMoveLoop calls
SetCapture.
There is already SetCapture in X11DesktopWindowMoveClient::RunMoveLoop which is
called from DesktopWindowTreeHostX11::RunMoveLoop so this should not be
necessary and I reverted this part of the change.

   // Activate may trigger a focus loss, destroying us.
   {
     base::WeakPtr<TabDragController> ref(weak_factory_.GetWeakPtr());
     browser->window()->Activate();
     if (!ref)
       return;
   }
   RunMoveLoop(drag_offset);
 }
 
@@ skipping 745 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);
 
 }