Use InterstitialPage through a delegate interface instead of deriving from it.

chrome/browser/chromeos/offline/offline_load_page.cc

Index: chrome/browser/chromeos/offline/offline_load_page.cc
===================================================================
--- chrome/browser/chromeos/offline/offline_load_page.cc	(revision 120576)
+++ chrome/browser/chromeos/offline/offline_load_page.cc	(working copy)
@@ -14,6 +14,7 @@
 #include "chrome/browser/chromeos/cros/network_library.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/renderer_preferences_util.h"
 #include "chrome/browser/tab_contents/tab_util.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
@@ -21,6 +22,7 @@
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/jstemplate_builder.h"
 #include "chrome/common/url_constants.h"
+#include "content/browser/tab_contents/interstitial_page.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/web_contents.h"
@@ -49,10 +51,13 @@
 OfflineLoadPage::OfflineLoadPage(WebContents* web_contents,
                                  const GURL& url,
                                  const CompletionCallback& callback)
-    : ChromeInterstitialPage(web_contents, true, url),
-      callback_(callback),
-      proceeded_(false) {
+    : callback_(callback),
+      proceeded_(false),
+      web_contents_(web_contents),
+      url_(url) {
   net::NetworkChangeNotifier::AddOnlineStateObserver(this);
+  interstitial_page_ = InterstitialPage::Create(web_contents, true, url, this);
+  interstitial_page_->Show();
 }
 
 OfflineLoadPage::~OfflineLoadPage() {
@@ -76,20 +81,21 @@
   bool rtl = base::i18n::IsRTL();
   strings.SetString("textdirection", rtl ? "rtl" : "ltr");
 
-  string16 failed_url(ASCIIToUTF16(url().spec()));
+  string16 failed_url(ASCIIToUTF16(url_.spec()));
   if (rtl)
     base::i18n::WrapStringWithLTRFormatting(&failed_url);
   strings.SetString("url", failed_url);
 
   // The offline page for app has icons and slightly different message.
-  Profile* profile = Profile::FromBrowserContext(tab()->GetBrowserContext());
+  Profile* profile = Profile::FromBrowserContext(
+      web_contents_->GetBrowserContext());
   DCHECK(profile);
   const Extension* extension = NULL;
   ExtensionService* extensions_service = profile->GetExtensionService();
   // Extension service does not exist in test.
   if (extensions_service)
     extension = extensions_service->extensions()->GetHostedAppByURL(
-        ExtensionURLInfo(url()));
+        ExtensionURLInfo(url_));
 
   if (extension)
     GetAppOfflineStrings(extension, failed_url, &strings);
@@ -102,6 +108,13 @@
   return jstemplate_builder::GetI18nTemplateHtml(html, &strings);
 }
 
+ void OfflineLoadPage::OverrideRendererPrefs(
+      content::RendererPreferences* prefs) {
+  Profile* profile = Profile::FromBrowserContext(
+      web_contents_->GetBrowserContext());
+  renderer_preferences_util::UpdateFromSystemSettings(prefs, profile);
+ }
+
 void OfflineLoadPage::GetAppOfflineStrings(
     const Extension* app,
     const string16& failed_url,
@@ -128,7 +141,7 @@
 
 void OfflineLoadPage::GetNormalOfflineStrings(
     const string16& failed_url, DictionaryValue* strings) const {
-  strings->SetString("title", tab()->GetTitle());
+  strings->SetString("title", web_contents_->GetTitle());
 
   // No icon for normal web site.
   strings->SetString("display_icon", "none");
@@ -173,7 +186,7 @@
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   proceeded_ = true;
   NotifyBlockingPageComplete(true);
-  InterstitialPage::Proceed();
+  interstitial_page_->Proceed();
 }
 
 void OfflineLoadPage::DontProceed() {
@@ -182,7 +195,7 @@
   if (proceeded_)
     return;
   NotifyBlockingPageComplete(false);
-  InterstitialPage::DontProceed();
+  interstitial_page_->DontProceed();
 }
 
 void OfflineLoadPage::OnOnlineStateChanged(bool online) {