WebContents created via ctrl-click should be in a new process (target=_blank).

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 <stddef.h>
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
@@ skipping 308 matching lines @@
     case WindowOpenDisposition::CURRENT_TAB:
       target = source;
       break;
 
     // Normally, the difference between NEW_POPUP and NEW_WINDOW is that a popup
     // should have no toolbar, no status bar, no menu bar, no scrollbars and be
     // not resizable.  For simplicity and to enable new testing scenarios in
     // content shell and layout tests, popups don't get special treatment below
     // (i.e. they will have a toolbar and other things described here).
     case WindowOpenDisposition::NEW_POPUP:
-    case WindowOpenDisposition::NEW_WINDOW: {
+    case WindowOpenDisposition::NEW_WINDOW:
+    // content_shell doesn't really support tabs, but some layout tests use
+    // middle click (which translates into kNavigationPolicyNewBackgroundTab),
+    // so we treat the cases below just like a NEW_WINDOW disposition.
+    case WindowOpenDisposition::NEW_BACKGROUND_TAB:
+    case WindowOpenDisposition::NEW_FOREGROUND_TAB: {
       Shell* new_window =
           Shell::CreateNewWindow(source->GetBrowserContext(),
                                  GURL(),  // Don't load anything just yet.
                                  params.source_site_instance,
                                  gfx::Size());  // Use default size.
       target = new_window->web_contents();
       if (switches::IsRunLayoutTestSwitchPresent())
         SecondaryTestWindowObserver::CreateForWebContents(target);
       break;
     }
 
     // No tabs in content_shell:
     case WindowOpenDisposition::SINGLETON_TAB:
-    case WindowOpenDisposition::NEW_FOREGROUND_TAB:
-    case WindowOpenDisposition::NEW_BACKGROUND_TAB:
     // No incognito mode in content_shell:
     case WindowOpenDisposition::OFF_THE_RECORD:
     // TODO(lukasza): Investigate if some layout tests might need support for
     // SAVE_TO_DISK disposition.  This would probably require that
     // BlinkTestController always sets up and cleans up a temporary directory
     // as the default downloads destinations for the duration of a test.
     case WindowOpenDisposition::SAVE_TO_DISK:
     // Ignoring requests with disposition == IGNORE_ACTION...
     case WindowOpenDisposition::IGNORE_ACTION:
     default:
@@ skipping 166 matching lines @@
   if (entry)
     PlatformSetTitle(entry->GetTitle());
 }
 
 void Shell::OnDevToolsWebContentsDestroyed() {
   devtools_observer_.reset();
   devtools_frontend_ = NULL;
 }
 
 }  // namespace content