Do not release capture when starting a move loop on Desktop Linux

ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.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 "ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.h"
 
 #include <X11/Xatom.h>
 
 #include "base/event_types.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop/message_loop.h"
 #include "third_party/skia/include/core/SkBitmap.h"
+#include "ui/aura/client/capture_client.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/clipboard/clipboard.h"
 #include "ui/base/dragdrop/drop_target_event.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/dragdrop/os_exchange_data_provider_aurax11.h"
 #include "ui/base/x/selection_utils.h"
 #include "ui/base/x/x11_foreign_window_manager.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/events/event.h"
@@ skipping 610 matching lines @@
         source_provider_->file_contents_name().AsUTF8Unsafe());
   }
   ui::SetAtomArrayProperty(xwindow_, "XdndActionList", "ATOM", actions);
 
   gfx::ImageSkia drag_image = source_provider_->GetDragImage();
   if (IsValidDragImage(drag_image)) {
     CreateDragWidget(drag_image);
     drag_widget_offset_ = source_provider_->GetDragImageOffset();
   }
 
+  // Chrome expects starting drag and drop to release capture.
+  aura::Window* capture_window =
+      aura::client::GetCaptureClient(root_window)->GetGlobalCaptureWindow();
+  if (capture_window)
+    capture_window->ReleaseCapture();
+
   // It is possible for the DesktopWindowTreeHostX11 to be destroyed during the
   // move loop, which would also destroy this drag-client. So keep track of
   // whether it is alive after the drag ends.
   base::WeakPtr<DesktopDragDropClientAuraX11> alive(
       weak_ptr_factory_.GetWeakPtr());
 
   // Windows has a specific method, DoDragDrop(), which performs the entire
   // drag. We have to emulate this, so we spin off a nested runloop which will
   // track all cursor movement and reroute events to a specific handler.
   move_loop_->RunMoveLoop(source_window, grab_cursor_);
@@ skipping 468 matching lines @@
     for (int x = 0; x < in_bitmap->width(); ++x) {
       if (SkColorGetA(in_row[x]) > kMinAlpha)
         return true;
     }
   }
 
   return false;
 }
 
 }  // namespace views