[Offline Pages] Fix PrerenderingLoader regression for handle a stop event from the prerender stack.

chrome/browser/android/offline_pages/prerendering_loader_unittest.cc

 // Copyright 2016 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 "chrome/browser/android/offline_pages/prerendering_loader.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/run_loop.h"
@@ skipping 218 matching lines @@
   EXPECT_TRUE(callback_called());
   EXPECT_EQ(Offliner::RequestStatus::LOADED, callback_load_status());
 
   // Consider Prerenderer stops (eg, times out) before Loader is done with it.
   test_adapter()->GetObserver()->OnPrerenderStop();
   PumpLoop();
   EXPECT_TRUE(loader()->IsIdle());
   EXPECT_FALSE(loader()->IsLoaded());
   EXPECT_EQ(Offliner::RequestStatus::PRERENDERING_CANCELED,
             callback_load_status());
+  EXPECT_FALSE(test_adapter()->IsActive());
 }
 
 TEST_F(PrerenderingLoaderTest, LoadPageLoadFailedNoContent) {
   test_adapter()->Configure(nullptr /* web_contents */,
                             prerender::FINAL_STATUS_MEMORY_LIMIT_EXCEEDED);
   GURL gurl("http://testit.sea");
   EXPECT_TRUE(loader()->IsIdle());
   EXPECT_TRUE(loader()->LoadPage(
       gurl,
       base::Bind(&PrerenderingLoaderTest::OnLoadDone, base::Unretained(this))));
@@ skipping 131 matching lines @@
   test_adapter()->FailStart();
   GURL gurl("http://testit.sea");
   EXPECT_TRUE(loader()->IsIdle());
   EXPECT_FALSE(loader()->LoadPage(
       gurl,
       base::Bind(&PrerenderingLoaderTest::OnLoadDone, base::Unretained(this))));
   EXPECT_TRUE(loader()->IsIdle());
 }
 
 }  // namespace offline_pages