Make PrerenderHandle an observer of PrerenderContents.

chrome/browser/prerender/prerender_tracker_unittest.cc

 // Copyright (c) 2012 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.
 
 #include <set>
 #include <utility>
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "chrome/browser/prerender/prerender_contents.h"
@@ skipping 40 matching lines @@
     prerendering_has_started_ = true;
     NotifyPrerenderStart();
   }
 
   void Cancel() {
     Destroy(FINAL_STATUS_CANCELLED);
   }
 
   void Use() {
     SetFinalStatus(FINAL_STATUS_USED);
+    PrepareForUse();
   }
 
  private:
   int child_id_;
   int route_id_;
 };
 
 class TestPrerenderManager : public PrerenderManager {
  public:
   explicit TestPrerenderManager(PrerenderTracker* prerender_tracker) :
@@ skipping 345 matching lines @@
   EXPECT_FALSE(prerender_tracker()->IsPrerenderingOnIOThread(
       kDefaultChildId, kDefaultRouteId));
 
   EXPECT_FALSE(prerender_tracker()->GetFinalStatus(
       kDefaultChildId + 1, kDefaultRouteId + 1, &final_status));
   EXPECT_FALSE(prerender_tracker()->IsPrerenderingOnIOThread(
       kDefaultChildId + 1, kDefaultRouteId + 1));
 }
 
 }  // namespace prerender