[DevTools] Fix crash in DevToolsWindow::ActivateContents.

chrome/browser/devtools/devtools_window.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/devtools/devtools_window.h"
 
 #include <algorithm>
 
 #include "base/json/json_reader.h"
 #include "base/metrics/histogram.h"
@@ skipping 822 matching lines @@
   bindings_->Reattach();
 
   content::NavigationController::LoadURLParams load_url_params(params.url);
   main_web_contents_->GetController().LoadURLWithParams(load_url_params);
   return main_web_contents_;
 }
 
 void DevToolsWindow::ActivateContents(WebContents* contents) {
   if (is_docked_) {
     WebContents* inspected_tab = GetInspectedWebContents();
-    inspected_tab->GetDelegate()->ActivateContents(inspected_tab);
+    if (inspected_tab)
+      inspected_tab->GetDelegate()->ActivateContents(inspected_tab);
   } else if (browser_) {
     browser_->window()->Activate();
   }
 }
 
 void DevToolsWindow::AddNewContents(WebContents* source,
                                     WebContents* new_contents,
                                     WindowOpenDisposition disposition,
                                     const gfx::Rect& initial_rect,
                                     bool user_gesture,
@@ skipping 365 matching lines @@
       closure.Run();
     return;
   }
   load_completed_callback_ = closure;
 }
 
 bool DevToolsWindow::ForwardKeyboardEvent(
     const content::NativeWebKeyboardEvent& event) {
   return event_forwarder_->ForwardEvent(event);
 }