gtk: Don't crash if the user double clicks an empty area of the task manager ...

chrome/browser/gtk/task_manager_gtk.cc

 // Copyright (c) 2009 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/gtk/task_manager_gtk.h"
 
 #include <gdk/gdkkeysyms.h>
 
 #include <algorithm>
 #include <vector>
@@ skipping 534 matching lines @@
   menu_controller_->RunMenu();
 }
 
 void TaskManagerGtk::ActivateFocusedTab() {
   GtkTreeSelection* selection = gtk_tree_view_get_selection(
       GTK_TREE_VIEW(treeview_));
 
   // If the user has just double clicked, only one item is selected.
   GtkTreeModel* model;
   GList* selected = gtk_tree_selection_get_selected_rows(selection, &model);
-  int row = GetRowNumForPath(reinterpret_cast<GtkTreePath*>(selected->data));
-  task_manager_->ActivateProcess(row);
+  if (selected) {
+    int row = GetRowNumForPath(reinterpret_cast<GtkTreePath*>(selected->data));
+    task_manager_->ActivateProcess(row);
+  }
 }
 
 void TaskManagerGtk::OnLinkActivated() {
   Browser* browser = BrowserList::GetLastActive();
   DCHECK(browser);
   browser->OpenURL(GURL("about:memory"), GURL(), NEW_FOREGROUND_TAB,
                    PageTransition::LINK);
   // In case the browser window is minimzed, show it. If this is an application
   // or popup, we can only have one tab, hence we need to process this in a
   // tabbed browser window. Currently, |browser| is pointing to the application,
@@ skipping 91 matching lines @@
   if (keyval == GDK_w && modifier == GDK_CONTROL_MASK) {
     // The GTK_RESPONSE_DELETE_EVENT response must be sent before the widget
     // is destroyed.  The deleted object will receive gtk signals otherwise.
     gtk_dialog_response(GTK_DIALOG(task_manager->dialog_),
                         GTK_RESPONSE_DELETE_EVENT);
     gtk_widget_destroy(task_manager->dialog_);
   }
 
   return TRUE;
 }