Don't do a default browser check when new tabs are opened via the command line.

chrome/browser/browser_init.cc

 // Copyright (c) 2006-2008 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/browser_init.h"
 
 #include <algorithm>
 
 #if defined(OS_WIN)
 #include "app/win_util.h"
@@ skipping 449 matching lines @@
         }
 
         if (open_splash) {
           browser->OpenURL(GURL("about:linux-splash"), GURL(),
                            NEW_FOREGROUND_TAB, PageTransition::START_PAGE);
         }
       }
     }
 #endif
     // Check whether we are the default browser.
-    if (!command_line_.HasSwitch(switches::kNoDefaultBrowserCheck))
+    if (process_startup &&
+        !command_line_.HasSwitch(switches::kNoDefaultBrowserCheck))
       CheckDefaultBrowser(profile);
   } else {
     RecordLaunchModeHistogram(LM_AS_WEBAPP);
   }
 
 #if defined(OS_WIN)
   // Print the selected page if the command line switch exists. Note that the
   // current selected tab would be the page which will be printed.
   if (command_line_.HasSwitch(switches::kPrint)) {
     Browser* browser = BrowserList::GetLastActive();
@@ skipping 369 matching lines @@
   scoped_refptr<AutomationProviderClass> automation =
       new AutomationProviderClass(profile);
   automation->ConnectToChannel(channel_id);
   automation->SetExpectedTabCount(expected_tabs);
 
   AutomationProviderList* list =
       g_browser_process->InitAutomationProviderList();
   DCHECK(list);
   list->AddProvider(automation);
 }