When printing a PDF, query and use the print scaling disabled option.

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/base/chrome_render_view_test.h"
 #include "content/public/renderer/render_view.h"
 #include "printing/print_job_constants.h"
@@ skipping 32 matching lines @@
   dict->SetBoolean(printing::kSettingCollate, false);
   dict->SetInteger(printing::kSettingColor, printing::GRAY);
   dict->SetBoolean(printing::kSettingPrintToPDF, true);
   dict->SetInteger(printing::kSettingDuplexMode, printing::SIMPLEX);
   dict->SetInteger(printing::kSettingCopies, 1);
   dict->SetString(printing::kSettingDeviceName, "dummy");
   dict->SetString(printing::kPreviewUIAddr, "0xb33fbeef");
   dict->SetInteger(printing::kPreviewRequestID, 12345);
   dict->SetBoolean(printing::kIsFirstRequest, true);
   dict->SetInteger(printing::kSettingMarginsType, printing::DEFAULT_MARGINS);
+  dict->SetBoolean(printing::kSettingPreviewModifiable, false);
   dict->SetBoolean(printing::kSettingHeaderFooterEnabled, false);
   dict->SetBoolean(printing::kSettingGenerateDraftData, true);
 }
 
 }  // namespace
 
 class PrintWebViewHelperTestBase : public ChromeRenderViewTest {
  public:
   PrintWebViewHelperTestBase() {}
   ~PrintWebViewHelperTestBase() {}
@@ skipping 472 matching lines @@
   // Fill in some dummy values.
   DictionaryValue dict;
   CreatePrintSettingsDictionary(&dict);
   OnPrintForPrintPreview(dict);
 
   VerifyPrintFailed(true);
   VerifyPagesPrinted(false);
 }
 
 #endif  // !defined(OS_CHROMEOS)