Remove dead code since PDFWebContentsHelper::ShowOpenInReaderPrompt isn't called anymore.

chrome/test/base/test_browser_window.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_TEST_BASE_TEST_BROWSER_WINDOW_H_
 #define CHROME_TEST_BASE_TEST_BROWSER_WINDOW_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "build/build_config.h"
@@ skipping 151 matching lines @@
     void FocusLocation(bool select_all) override {}
     void FocusSearch() override {}
     void UpdateContentSettingsIcons() override {}
     void UpdateManagePasswordsIconAndBubble() override {}
     void UpdateSaveCreditCardIcon() override {}
     void UpdatePageActions() override {}
     void UpdateBookmarkStarVisibility() override {}
     void UpdateLocationBarVisibility(bool visible, bool animate) override {}
     bool ShowPageActionPopup(const extensions::Extension* extension,
                              bool grant_active_tab) override;
-    void UpdateOpenPDFInReaderPrompt() override {}
     void SaveStateToContents(content::WebContents* contents) override {}
     void Revert() override {}
     const OmniboxView* GetOmniboxView() const override;
     OmniboxView* GetOmniboxView() override;
     LocationBarTesting* GetLocationBarForTesting() override;
 
    private:
     DISALLOW_COPY_AND_ASSIGN(TestLocationBar);
   };
 
@@ skipping 20 matching lines @@
 
 namespace chrome {
 
 // Helper that handle the lifetime of TestBrowserWindow instances.
 std::unique_ptr<Browser> CreateBrowserWithTestWindowForParams(
     Browser::CreateParams* params);
 
 }  // namespace chrome
 
 #endif  // CHROME_TEST_BASE_TEST_BROWSER_WINDOW_H_