Print Preview: Add "print preview" back to about:flags; enable it by default just once.

chrome/browser/ui/webui/print_preview_ui_uitest.cc

 // 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.
 
 #include "base/string16.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/automation/browser_proxy.h"
 #include "chrome/test/automation/tab_proxy.h"
 #include "chrome/test/ui/ui_test.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 
 namespace {
 
 class PrintPreviewUITest : public UITest {
  public:
   PrintPreviewUITest() {
     dom_automation_enabled_ = true;
-#if !defined(GOOGLE_CHROME_BUILD) || defined(OS_CHROMEOS) || defined(OS_MACOSX)
     launch_arguments_.AppendSwitch(switches::kEnablePrintPreview);
-#endif
   }
 
   void AssertIsPrintPage(TabProxy* tab) {
     std::wstring title;
     ASSERT_TRUE(tab->GetTabTitle(&title));
     string16 expected_title =
         l10n_util::GetStringUTF16(IDS_PRINT_PREVIEW_TITLE);
     ASSERT_EQ(expected_title, WideToUTF16Hack(title));
   }
 };
@@ skipping 32 matching lines @@
   ASSERT_TRUE(browser->GetTabCount(&tab_count));
   ASSERT_EQ(2, tab_count);
   scoped_refptr<TabProxy> tab = browser->GetActiveTab();
   ASSERT_TRUE(tab.get());
   AssertIsPrintPage(tab);
   ASSERT_TRUE(browser->IsMenuCommandEnabled(IDC_PRINT, &enabled));
   ASSERT_FALSE(enabled);
 }
 
 }  // namespace