content_shell: avoid debug crashing for mid-clicks on links.

content/shell/browser/shell.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 "content/shell/browser/shell.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
@@ skipping 212 matching lines @@
 }
 
 gfx::NativeView Shell::GetContentView() {
   if (!web_contents_)
     return NULL;
   return web_contents_->GetView()->GetNativeView();
 }
 
 WebContents* Shell::OpenURLFromTab(WebContents* source,
                                    const OpenURLParams& params) {
-  // The only one we implement for now.
-  DCHECK(params.disposition == CURRENT_TAB);
+  // CURRENT_TAB is the only one we implement for now.
+  if (params.disposition != CURRENT_TAB)
+      return NULL;
   NavigationController::LoadURLParams load_url_params(params.url);
   load_url_params.referrer = params.referrer;
   load_url_params.transition_type = params.transition;
   load_url_params.extra_headers = params.extra_headers;
   load_url_params.should_replace_current_entry =
       params.should_replace_current_entry;
 
   if (params.transferred_global_request_id != GlobalRequestID()) {
     load_url_params.is_renderer_initiated = params.is_renderer_initiated;
     load_url_params.transferred_global_request_id =
@@ skipping 113 matching lines @@
     NOTREACHED();
   }
 }
 
 void Shell::OnDevToolsWebContentsDestroyed() {
   devtools_observer_.reset();
   devtools_frontend_ = NULL;
 }
 
 }  // namespace content