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

chrome/renderer/print_web_view_helper_browsertest.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 "chrome/common/chrome_switches.h"
 #include "chrome/common/print_messages.h"
 #include "chrome/renderer/print_web_view_helper.h"
 #include "chrome/test/render_view_test.h"
 #include "printing/print_job_constants.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 82 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(PrintWebViewHelperTestBase);
 };
 
 class PrintWebViewHelperTest : public PrintWebViewHelperTestBase {
  public:
   PrintWebViewHelperTest() {}
   virtual ~PrintWebViewHelperTest() {}
 
   virtual void SetUp() {
-    // Append the print preview switch before creating the PrintWebViewHelper.
-#if defined(GOOGLE_CHROME_BUILD) && !defined(OS_CHROMEOS) && !defined(OS_MACOSX)
-    CommandLine::ForCurrentProcess()->AppendSwitch(
-        switches::kDisablePrintPreview);
-#endif
-
     RenderViewTest::SetUp();
   }
 
  protected:
   DISALLOW_COPY_AND_ASSIGN(PrintWebViewHelperTest);
 };
 
 // Tests that printing pages work and sending and receiving messages through
 // that channel all works.
 TEST_F(PrintWebViewHelperTest, OnPrintPages) {
@@ skipping 175 matching lines @@
 
 // These print preview tests do not work on Chrome OS yet.
 #if !defined(OS_CHROMEOS)
 class PrintWebViewHelperPreviewTest : public PrintWebViewHelperTestBase {
  public:
   PrintWebViewHelperPreviewTest() {}
   virtual ~PrintWebViewHelperPreviewTest() {}
 
   virtual void SetUp() {
     // Append the print preview switch before creating the PrintWebViewHelper.
-#if !defined(GOOGLE_CHROME_BUILD) || defined(OS_MACOSX)
     CommandLine::ForCurrentProcess()->AppendSwitch(
         switches::kEnablePrintPreview);
-#endif
 
     RenderViewTest::SetUp();
   }
 
  protected:
   void VerifyPrintPreviewFailed(bool did_fail) {
     bool print_preview_failed = (render_thread_.sink().GetUniqueMessageMatching(
         PrintHostMsg_PrintPreviewFailed::ID) != NULL);
     EXPECT_EQ(did_fail, print_preview_failed);
   }
@@ skipping 71 matching lines @@
   LoadHTML(kPrintPreviewHTML);
 
   // An empty dictionary should fail.
   DictionaryValue empty_dict;
   PrintWebViewHelper::Get(view_)->OnPrintForPrintPreview(empty_dict);
 
   VerifyPrintFailed(true);
   VerifyPagesPrinted(false);
 }
 #endif  // !defined(OS_CHROMEOS)