[OfflinePages] Improve visiblity/handling of "Loading not started" case

chrome/browser/android/offline_pages/prerender_adapter.cc

Index: chrome/browser/android/offline_pages/prerender_adapter.cc
diff --git a/chrome/browser/android/offline_pages/prerender_adapter.cc b/chrome/browser/android/offline_pages/prerender_adapter.cc
index cf568a5949fbd8498c9581e8ccc0ed64ecfcb34e..f780cfc4fa265c21d16c671110a8d1e38abc0e3d 100644
--- a/chrome/browser/android/offline_pages/prerender_adapter.cc
+++ b/chrome/browser/android/offline_pages/prerender_adapter.cc
@@ -25,17 +25,12 @@ PrerenderAdapter::~PrerenderAdapter() {
     DestroyActive();
 }
 
-bool PrerenderAdapter::CanPrerender() const {
-  return prerender::PrerenderManager::IsPrerenderingPossible();
-}
-
 bool PrerenderAdapter::StartPrerender(
     content::BrowserContext* browser_context,
     const GURL& url,
     content::SessionStorageNamespace* session_storage_namespace,
     const gfx::Size& size) {
   DCHECK(!IsActive());
-  DCHECK(CanPrerender());
 
   prerender::PrerenderManager* manager =
       prerender::PrerenderManagerFactory::GetForBrowserContext(browser_context);