Fix pressing enter key crashes overview mode without a selection.

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 182 matching lines @@
   // TODO(nsatragno): Use the previous index for more than two displays.
   selected_grid_index_ = 0;
   if (grid_list_.empty())
     CancelSelection();
 }
 
 void WindowSelector::OnKeyEvent(ui::KeyEvent* event) {
   if (event->type() != ui::ET_KEY_PRESSED)
     return;
 
-  bool handled = true;
   switch (event->key_code()) {
     case ui::VKEY_ESCAPE:
       CancelSelection();
       break;
     case ui::VKEY_UP:
       Move(WindowSelector::UP);
       break;
     case ui::VKEY_DOWN:
       Move(WindowSelector::DOWN);
       break;
     case ui::VKEY_RIGHT:
       Move(WindowSelector::RIGHT);
       break;
     case ui::VKEY_LEFT:
       Move(WindowSelector::LEFT);
       break;
     case ui::VKEY_RETURN:
-      wm::GetWindowState(
-          grid_list_[selected_grid_index_]->
-              SelectedWindow()->SelectionWindow())->Activate();
+      // Ignore if no item is selected.
+      if (!grid_list_[selected_grid_index_]->is_selecting())
+        return;
+      wm::GetWindowState(grid_list_[selected_grid_index_]->
+                         SelectedWindow()->SelectionWindow())->Activate();
       break;
     default:
       // Not a key we are interested in.
-      handled = false;
-      break;
+      return;
   }
-  if (handled)
-    event->SetHandled();
+  event->StopPropagation();
 }
 
 void WindowSelector::OnDisplayAdded(const gfx::Display& display) {
 }
 
 void WindowSelector::OnDisplayRemoved(const gfx::Display& display) {
   // TODO(nsatragno): Keep window selection active on remaining displays.
   CancelSelection();
 }
 
@@ skipping 123 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