Defer preparing for overview until all overview items are initialized.

ash/wm/overview/window_selector.cc

 // Copyright 2013 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 "ash/wm/overview/window_selector.h"
 
 #include <algorithm>
 
 #include "ash/accessibility_delegate.h"
 #include "ash/ash_switches.h"
@@ skipping 106 matching lines @@
       container->AddObserver(this);
       observed_windows_.insert(container);
     }
     scoped_ptr<WindowGrid> grid(new WindowGrid(*iter, windows, this));
     if (grid->empty())
       continue;
     num_items_ += grid->size();
     grid_list_.push_back(grid.release());
   }
 
+  // Do not call PrepareForOverview until all items are added to window_list_ as
+  // we don't want to cause any window updates until all windows in overview
+  // are observed. See http://crbug.com/384495.
+  for (ScopedVector<WindowGrid>::iterator iter = grid_list_.begin();
+       iter != grid_list_.end(); ++iter) {
+    (*iter)->PrepareForOverview();
+    (*iter)->PositionWindows(true);
+  }
+
   DCHECK(!grid_list_.empty());
   UMA_HISTOGRAM_COUNTS_100("Ash.WindowSelector.Items", num_items_);
 
   shell->activation_client()->AddObserver(this);
 
   // Remove focus from active window before entering overview.
   aura::client::GetFocusClient(
       Shell::GetPrimaryRootWindow())->FocusWindow(NULL);
 
   shell->PrependPreTargetHandler(this);
@@ skipping 249 matching lines @@
     // root window, identify it and call Move() on it to initialize the
     // selection widget.
     // TODO(nsatragno): If there are more than two monitors, move between grids
     // in the requested direction.
     selected_grid_index_ = (selected_grid_index_ + 1) % grid_list_.size();
     grid_list_[selected_grid_index_]->Move(direction);
   }
 }
 
 }  // namespace ash