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

chrome/browser/android/offline_pages/prerendering_loader.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/location.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 166 matching lines @@
   // state, and post callback.
   // Note: it is possible to receive some asynchronous stopped indication after
   // the request has completed/stopped via another path so the Loader may be
   // idle at this point.
 
   if (IsIdle())
     return;
 
   Offliner::RequestStatus request_status;
 
-  if (IsLoaded()) {
-    // If page already loaded, then prerender is telling us that it is
-    // canceling (and we should stop using the loaded WebContents).
-    request_status = Offliner::RequestStatus::PRERENDERING_CANCELED;
-  } else if (adapter_->IsActive()) {
-    // Get the available FinalStatus to better identify the outcome.
-    prerender::FinalStatus final_status = adapter_->GetFinalStatus();
-    DVLOG(1) << "Load failed: " << final_status;
-    request_status = ClassifyFinalStatus(final_status);
+  if (adapter_->IsActive()) {
+    if (IsLoaded()) {
+      // If page already loaded, then prerender is telling us that it is
+      // canceling (and we should stop using the loaded WebContents).
+      request_status = Offliner::RequestStatus::PRERENDERING_CANCELED;
+    } else {
+      // Otherwise, get the available FinalStatus to classify the outcome.
+      prerender::FinalStatus final_status = adapter_->GetFinalStatus();
+      DVLOG(1) << "Load failed: " << final_status;
+      request_status = ClassifyFinalStatus(final_status);
 
-    // Loss of network connection can show up as unsupported scheme per
-    // a redirect to a special data URL is used to navigate to error page.
-    // Capture the current connectivity here in case we can leverage that
-    // to differentiate how to treat it.
-    if (final_status == prerender::FINAL_STATUS_UNSUPPORTED_SCHEME) {
-      UMA_HISTOGRAM_ENUMERATION(
-          "OfflinePages.Background.UnsupportedScheme.ConnectionType",
-          net::NetworkChangeNotifier::GetConnectionType(),
-          net::NetworkChangeNotifier::ConnectionType::CONNECTION_LAST + 1);
+      // Loss of network connection can show up as unsupported scheme per
+      // a redirect to a special data URL is used to navigate to error page.
+      // Capture the current connectivity here in case we can leverage that
+      // to differentiate how to treat it.
+      if (final_status == prerender::FINAL_STATUS_UNSUPPORTED_SCHEME) {
+        UMA_HISTOGRAM_ENUMERATION(
+            "OfflinePages.Background.UnsupportedScheme.ConnectionType",
+            net::NetworkChangeNotifier::GetConnectionType(),
+            net::NetworkChangeNotifier::ConnectionType::CONNECTION_LAST + 1);
+      }
     }
+
+    // Now clean up the active prerendering operation detail.
     adapter_->DestroyActive();
   } else {
     // No access to FinalStatus so classify as retryable failure.
     request_status = Offliner::RequestStatus::PRERENDERING_FAILED;
   }
 
   snapshot_controller_.reset(nullptr);
   session_contents_.reset(nullptr);
   state_ = State::IDLE;
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(callback_, request_status, nullptr));
 }
 
 void PrerenderingLoader::CancelPrerender() {
   if (adapter_->IsActive()) {
     adapter_->DestroyActive();
   }
   snapshot_controller_.reset(nullptr);
   session_contents_.reset(nullptr);
   state_ = State::IDLE;
 }
 
 }  // namespace offline_pages