[Offline pages] Fix crashing snapshot controller and reorganize reset code for easier test maintena…

chrome/browser/android/offline_pages/background_loader_offliner_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/background_loader_offliner.h"
 
 #include "base/bind.h"
 #include "base/run_loop.h"
 #include "base/test/histogram_tester.h"
 #include "base/test/scoped_feature_list.h"
@@ skipping 26 matching lines @@
 const int64_t kRequestId = 7;
 const GURL kHttpUrl("http://www.tunafish.com");
 const GURL kFileUrl("file://salmon.png");
 const ClientId kClientId("async_loading", "88");
 const bool kUserRequested = true;
 
 // Mock OfflinePageModel for testing the SavePage calls
 class MockOfflinePageModel : public StubOfflinePageModel {
  public:
   MockOfflinePageModel() : mock_saving_(false), mock_deleting_(false) {}
-  ~MockOfflinePageModel() override {}
+  ~MockOfflinePageModel() override {
+    DVLOG(0) << "Offline page model destroyed";
+  }
 
   void SavePage(const SavePageParams& save_page_params,
                 std::unique_ptr<OfflinePageArchiver> archiver,
                 const SavePageCallback& callback) override {
     mock_saving_ = true;
     save_page_callback_ = callback;
   }
 
   void CompleteSavingAsArchiveCreationFailed() {
     DCHECK(mock_saving_);
@@ skipping 582 matching lines @@
   CompleteLoading();
   PumpLoop();
 
   // One extra part should be added if the flag is on.
   content::MHTMLExtraParts* extra_parts =
       content::MHTMLExtraParts::FromWebContents(offliner()->web_contents());
   EXPECT_EQ(extra_parts->size(), 1);
 }
 
 }  // namespace offline_pages