Revert of Showing previews UI for Offline Previews

chrome/browser/previews/previews_infobar_tab_helper.h

 // Copyright 2016 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_BROWSER_PREVIEWS_PREVIEWS_INFOBAR_TAB_HELPER_H_
 #define CHROME_BROWSER_PREVIEWS_PREVIEWS_INFOBAR_TAB_HELPER_H_
 
 #include "base/macros.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
@@ skipping 17 matching lines @@
     return displayed_preview_infobar_;
   }
 
   // Sets whether the InfoBar for a preview has been shown for the page.
   // |displayed_preview_infobar_| is reset to false on
   // DidStartProvisionalLoadForFrame for the main frame.
   void set_displayed_preview_infobar(bool displayed) {
     displayed_preview_infobar_ = displayed;
   }
 
-  // Whether an offline preview has been shown for this page.
-  bool is_showing_offline_preview() const {
-    return is_showing_offline_preview_;
-  }
-
  private:
   friend class content::WebContentsUserData<PreviewsInfoBarTabHelper>;
   friend class PreviewsInfoBarTabHelperUnitTest;
 
   explicit PreviewsInfoBarTabHelper(content::WebContents* web_contents);
 
   // Overridden from content::WebContentsObserver:
+  void DidStartProvisionalLoadForFrame(
+      content::RenderFrameHost* render_frame_host,
+      const GURL& validated_url,
+      bool is_error_page,
+      bool is_iframe_srcdoc) override;
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override;
 
   // True if the InfoBar for a preview has been shown for the page.
   bool displayed_preview_infobar_;
 
-  // Whether an offline preview has been shown for this page.
-  bool is_showing_offline_preview_;
-
   DISALLOW_COPY_AND_ASSIGN(PreviewsInfoBarTabHelper);
 };
 
 #endif  // CHROME_BROWSER_PREVIEWS_PREVIEWS_INFOBAR_TAB_HELPER_H_