Respect command line flags for interstitial pages.

InterstitialPage implements RenderViewHostDelegate but does
not override GetWebkitPrefs() which in the base class only
returns default settings. For example, this does not allow 
compositing for interstitial pages ever.

BUG=
TEST=


Review URL: http://codereview.chromium.org/8826013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113352 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/tab_contents/interstitial_page.cc

@@ -393,6 +393,11 @@ content::RendererPreferences InterstitialPage::GetRendererPrefs(
   return renderer_preferences_;
 }
 
+WebPreferences InterstitialPage::GetWebkitPrefs() {
+  return content::GetContentClient()->browser()->GetWebkitPrefs(
+      render_view_host());
+}
+
 RenderViewHost* InterstitialPage::CreateRenderViewHost() {
   RenderViewHost* render_view_host = new RenderViewHost(
       SiteInstance::CreateSiteInstance(tab()->browser_context()),

content/browser/tab_contents/interstitial_page.h

@@ -131,6 +131,7 @@ class CONTENT_EXPORT InterstitialPage : public content::NotificationObserver,
                            base::i18n::TextDirection title_direction) OVERRIDE;
   virtual content::RendererPreferences GetRendererPrefs(
       content::BrowserContext* browser_context) const OVERRIDE;
+  virtual WebPreferences GetWebkitPrefs() OVERRIDE;
 
   // Invoked with the NavigationEntry that is going to be added to the
   // navigation controller.