Mac: Turn on tab overview mode by default.

chrome/browser/app_controller_mac.mm

 // Copyright (c) 2011 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.
 
 #import "chrome/browser/app_controller_mac.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/mac/mac_util.h"
@@ skipping 591 matching lines @@
 
   startupComplete_ = YES;
 
   // TODO(viettrungluu): This is very temporary, since this should be done "in"
   // |BrowserMain()|, i.e., this list of startup URLs should be appended to the
   // (probably-empty) list of URLs from the command line.
   if (startupUrls_.size()) {
     [self openUrls:startupUrls_];
     [self clearStartupUrls];
   }
-
-  const CommandLine& parsed_command_line = *CommandLine::ForCurrentProcess();
-  if (!parsed_command_line.HasSwitch(switches::kEnableExposeForTabs)) {
-    [tabposeMenuItem_ setHidden:YES];
-  }
 }
 
 // This is called after profiles have been loaded and preferences registered.
 // It is safe to access the default profile here.
 - (void)applicationDidBecomeActive:(NSNotification*)notify {
   NotificationService::current()->Notify(NotificationType::APP_ACTIVATED,
                                          NotificationService::AllSources(),
                                          NotificationService::NoDetails());
 }
 
@@ skipping 662 matching lines @@
   [appController showPreferencesWindow:nil page:page profile:profile];
 }
 
 namespace app_controller_mac {
 
 bool IsOpeningNewWindow() {
   return g_is_opening_new_window;
 }
 
 }  // namespace app_controller_mac