[Offline Pages] Fixes PrerenderingLoader bug to clear session_contents_ when PrerenderManager does …

chrome/browser/android/offline_pages/prerendering_loader.cc

Index: chrome/browser/android/offline_pages/prerendering_loader.cc
diff --git a/chrome/browser/android/offline_pages/prerendering_loader.cc b/chrome/browser/android/offline_pages/prerendering_loader.cc
index 2584933c487dc4fe7788b1e07ae5e5eec829e0e0..e3579c5fa1193308e701a6904b059b3813e7865e 100644
--- a/chrome/browser/android/offline_pages/prerendering_loader.cc
+++ b/chrome/browser/android/offline_pages/prerendering_loader.cc
@@ -49,8 +49,10 @@ bool PrerenderingLoader::LoadPage(const GURL& url,
   gfx::Size renderWindowSize = session_contents_->GetContainerBounds().size();
   bool accepted = adapter_->StartPrerender(
       browser_context_, url, sessionStorageNamespace, renderWindowSize);
-  if (!accepted)
+  if (!accepted) {
+    session_contents_.reset(nullptr);

[dewittj, 2016/09/13 17:03:17]

It is unfortunate that we have to create a web contents only to destroy it
immediately afterwards.  I suppose there's no way to do this without it?

[dougarnett, 2016/09/13 18:15:22]

Acknowledged.

     return false;
+  }
 
   DCHECK(adapter_->IsActive());
   snapshot_controller_.reset(