PrerenderingOffliner will abort background load if it sees chrome transitioning to foreground on lo…

chrome/browser/android/offline_pages/prerendering_offliner.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_offliner.h"
 
 #include "base/bind.h"
+#include "base/sys_info.h"
 #include "chrome/browser/android/offline_pages/offline_page_mhtml_archiver.h"
 #include "components/offline_pages/background/save_page_request.h"
 #include "components/offline_pages/offline_page_model.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/web_contents.h"
 
 namespace offline_pages {
 
 PrerenderingOffliner::PrerenderingOffliner(
     content::BrowserContext* browser_context,
     const OfflinerPolicy* policy,
     OfflinePageModel* offline_page_model)
     : browser_context_(browser_context),
       offline_page_model_(offline_page_model),
       pending_request_(nullptr),
+      is_low_end_device_(base::SysInfo::IsLowEndDevice()),
+      app_listener_(nullptr),
       weak_ptr_factory_(this) {}
 
 PrerenderingOffliner::~PrerenderingOffliner() {}
 
 void PrerenderingOffliner::OnLoadPageDone(
     const SavePageRequest& request,
-    const CompletionCallback& completion_callback,
     Offliner::RequestStatus load_status,
     content::WebContents* web_contents) {
   // Check if request is still pending receiving a callback.
   // Note: it is possible to get a loaded page, start the save operation,
   // and then get another callback from the Loader (eg, if its loaded
   // WebContents is being destroyed for some resource reclamation).
   if (!pending_request_)
     return;
 
   // Since we are able to stop/cancel a previous load request, we should
@@ skipping 14 matching lines @@
     std::unique_ptr<OfflinePageArchiver> archiver(
         new OfflinePageMHTMLArchiver(web_contents));
     // Pass in the URL from the WebContents in case it is redirected from
     // the requested URL. This is to work around a check in the
     // OfflinePageModel implementation that ensures URL passed in here is
     // same as LastCommittedURL from the snapshot.
     // TODO(dougarnett): Raise issue of how to better deal with redirects.
     SavePage(web_contents->GetLastCommittedURL(), request.client_id(),
              std::move(archiver),
              base::Bind(&PrerenderingOffliner::OnSavePageDone,
-                        weak_ptr_factory_.GetWeakPtr(), request,
-                        completion_callback));
+                        weak_ptr_factory_.GetWeakPtr(), request));
   } else {
-    // Clear pending request and then run the completion callback.
+    // Clear pending request and then run its completion callback.
     pending_request_.reset(nullptr);
-    completion_callback.Run(request, load_status);
+    app_listener_.reset(nullptr);

[fgorski, 2016/07/19 16:09:44]

nit: this does not match the comment and is in between commented code. It could
happen before the commented block or after.

[dougarnett, 2016/07/19 17:40:50]

Revised comments to include.

+    completion_callback_.Run(request, load_status);
   }
 }
 
 void PrerenderingOffliner::OnSavePageDone(
     const SavePageRequest& request,
-    const CompletionCallback& completion_callback,
     SavePageResult save_result,
     int64_t offline_id) {
   // Check if request is still pending receiving a callback.
   if (!pending_request_)
     return;
 
-  // Also check that save callback is for same request as pending request
+  // Also check that this completed request is same as the pending one
   // (since SavePage request is not cancel-able currently and could be old).
   if (request.request_id() != pending_request_->request_id()) {
     DVLOG(1) << "Ignoring save callback for old request";
     return;
   }
 
   // Clear pending request here and inform loader we are done with WebContents.
   pending_request_.reset(nullptr);
+  app_listener_.reset(nullptr);
   GetOrCreateLoader()->StopLoading();
 
   // Determine status and run the completion callback.
   Offliner::RequestStatus save_status;
   if (save_result == SavePageResult::SUCCESS) {
     save_status = RequestStatus::SAVED;
   } else {
     // TODO(dougarnett): Consider reflecting some recommendation to retry the
     // request based on specific save error cases.
     save_status = RequestStatus::SAVE_FAILED;
   }
-  completion_callback.Run(request, save_status);
+  completion_callback_.Run(request, save_status);
 }
 
 bool PrerenderingOffliner::LoadAndSave(const SavePageRequest& request,
                                        const CompletionCallback& callback) {
   if (pending_request_) {
     DVLOG(1) << "Already have pending request";
     return false;
   }
 
   if (!GetOrCreateLoader()->CanPrerender()) {
     DVLOG(1) << "Prerendering not allowed/configured";
     return false;
   }
 
   if (!OfflinePageModel::CanSaveURL(request.url())) {
     DVLOG(1) << "Not able to save page for requested url: " << request.url();
     return false;
   }
 
   // Track copy of pending request for callback handling.
   pending_request_.reset(new SavePageRequest(request));
+  completion_callback_ = callback;
 
   // Kick off load page attempt.
   bool accepted = GetOrCreateLoader()->LoadPage(
-      request.url(),
-      base::Bind(&PrerenderingOffliner::OnLoadPageDone,
-                 weak_ptr_factory_.GetWeakPtr(), request, callback));
-  if (!accepted)
+      request.url(), base::Bind(&PrerenderingOffliner::OnLoadPageDone,
+                                weak_ptr_factory_.GetWeakPtr(), request));
+  if (!accepted) {
     pending_request_.reset(nullptr);
+  } else {
+    app_listener_.reset(new base::android::ApplicationStatusListener(
+        base::Bind(&PrerenderingOffliner::OnApplicationStateChange,
+                   weak_ptr_factory_.GetWeakPtr())));
+  }
 
   return accepted;
 }
 
 void PrerenderingOffliner::Cancel() {
   if (pending_request_) {
     pending_request_.reset(nullptr);
+    app_listener_.reset(nullptr);
     GetOrCreateLoader()->StopLoading();
     // TODO(dougarnett): Consider ability to cancel SavePage request.
   }
 }
 
 void PrerenderingOffliner::SetLoaderForTesting(
     std::unique_ptr<PrerenderingLoader> loader) {
   DCHECK(!loader_);
   loader_ = std::move(loader);
 }
 
+void PrerenderingOffliner::SetLowEndDeviceForTesting(bool is_low_end_device) {
+  is_low_end_device_ = is_low_end_device;
+}
+
+void PrerenderingOffliner::SetApplicationStateForTesting(
+    base::android::ApplicationState application_state) {
+  OnApplicationStateChange(application_state);
+}
+
 void PrerenderingOffliner::SavePage(
     const GURL& url,
     const ClientId& client_id,
     std::unique_ptr<OfflinePageArchiver> archiver,
-    const SavePageCallback& callback) {
+    const SavePageCallback& save_callback) {
   DCHECK(offline_page_model_);
-  offline_page_model_->SavePage(url, client_id, std::move(archiver), callback);
+  offline_page_model_->SavePage(url, client_id, std::move(archiver),
+                                save_callback);
 }
 
 PrerenderingLoader* PrerenderingOffliner::GetOrCreateLoader() {
   if (!loader_) {
     loader_.reset(new PrerenderingLoader(browser_context_));
   }
   return loader_.get();
 }
 
+void PrerenderingOffliner::OnApplicationStateChange(
+    base::android::ApplicationState application_state) {
+  if (pending_request_ && is_low_end_device_ &&
+      application_state ==
+          base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES) {
+    DVLOG(1) << "App became active, canceling current offlining request";
+    SavePageRequest* request = pending_request_.get();
+    Cancel();
+    completion_callback_.Run(*request,
+                             Offliner::RequestStatus::FOREGROUND_CANCELED);
+  }
+}
+
 }  // namespace offline_pages