Only distill unread items

BUG=672774

Review-Url: https://codereview.chromium.org/2565753002
Cr-Commit-Position: refs/heads/master@{#437534}

components/reading_list/ios/reading_list_model_impl.cc

@@ -170,8 +170,11 @@ ReadingListEntry* ReadingListModelImpl::SyncMergeEntry(
   } else {
     unread_entry_count_++;
   }
-  for (auto& observer : observers_)
+  for (auto& observer : observers_) {
+    observer.ReadingListDidMoveEntry(this, url);
     observer.ReadingListDidApplyChanges(this);
+  }
+
   return existing_entry;
 }
 
@@ -263,6 +266,7 @@ void ReadingListModelImpl::SetReadStatus(const GURL& url, bool read) {
     storage_layer_->SaveEntry(entry);
   }
   for (ReadingListModelObserver& observer : observers_) {
+    observer.ReadingListDidMoveEntry(this, url);
     observer.ReadingListDidApplyChanges(this);
   }
 }

components/reading_list/ios/reading_list_model_observer.h

@@ -45,6 +45,12 @@ class ReadingListModelObserver {
   virtual void ReadingListWillMoveEntry(const ReadingListModel* model,
                                         const GURL& url) {}
 
+  // Invoked when elements |MarkEntryUpdated| has been called on an entry. This
+  // means that the order of the entry may have changed and read/unread list may
+  // have changed too.
+  virtual void ReadingListDidMoveEntry(const ReadingListModel* model,
+                                       const GURL& url) {}
+
   // Invoked when elements are added.
   virtual void ReadingListWillAddEntry(const ReadingListModel* model,
                                        const ReadingListEntry& entry) {}

ios/chrome/browser/reading_list/reading_list_download_service.cc

@@ -84,7 +84,23 @@ void ReadingListDownloadService::ReadingListDidAddEntry(
     const ReadingListModel* model,
     const GURL& url) {
   DCHECK_EQ(reading_list_model_, model);
-  ScheduleDownloadEntry(url);
+  ProcessNewEntry(url);
+}
+
+void ReadingListDownloadService::ReadingListDidMoveEntry(
+    const ReadingListModel* model,
+    const GURL& url) {
+  DCHECK_EQ(reading_list_model_, model);
+  ProcessNewEntry(url);
+}
+
+void ReadingListDownloadService::ProcessNewEntry(const GURL& url) {
+  const ReadingListEntry* entry = reading_list_model_->GetEntryByURL(url);
+  if (!entry || entry->IsRead()) {
+    url_downloader_->CancelDownloadOfflineURL(url);
+  } else {
+    ScheduleDownloadEntry(url);
+  }
 }
 
 void ReadingListDownloadService::DownloadAllEntries() {
@@ -98,7 +114,7 @@ void ReadingListDownloadService::ScheduleDownloadEntry(const GURL& url) {
   DCHECK(reading_list_model_->loaded());
   const ReadingListEntry* entry = reading_list_model_->GetEntryByURL(url);
   if (!entry || entry->DistilledState() == ReadingListEntry::ERROR ||
-      entry->DistilledState() == ReadingListEntry::PROCESSED)
+      entry->DistilledState() == ReadingListEntry::PROCESSED || entry->IsRead())
     return;
   GURL local_url(url);
   web::WebThread::PostDelayedTask(
@@ -112,7 +128,7 @@ void ReadingListDownloadService::DownloadEntry(const GURL& url) {
   DCHECK(reading_list_model_->loaded());
   const ReadingListEntry* entry = reading_list_model_->GetEntryByURL(url);
   if (!entry || entry->DistilledState() == ReadingListEntry::ERROR ||
-      entry->DistilledState() == ReadingListEntry::PROCESSED)
+      entry->DistilledState() == ReadingListEntry::PROCESSED || entry->IsRead())
     return;
 
   if (net::NetworkChangeNotifier::IsOffline()) {

ios/chrome/browser/reading_list/reading_list_download_service.h

@@ -50,11 +50,15 @@ class ReadingListDownloadService
                                   const GURL& url) override;
   void ReadingListDidAddEntry(const ReadingListModel* model,
                               const GURL& url) override;
+  void ReadingListDidMoveEntry(const ReadingListModel* model,
+                               const GURL& url) override;
 
  private:
   // Tries to save offline versions of all entries in the reading list that are
   // not yet saved. Must only be called after reading list model is loaded.
   void DownloadAllEntries();
+  // Processes a new entry and schedule a download if needed.
+  void ProcessNewEntry(const GURL& url);
   // Schedule a download of an offline version of the reading list entry,
   // according to the delay of the entry. Must only be called after reading list
   // model is loaded.

ios/chrome/browser/reading_list/url_downloader.cc

@@ -50,9 +50,7 @@ void URLDownloader::OfflineURLExists(const GURL& url,
 
 void URLDownloader::RemoveOfflineURL(const GURL& url) {
   // Remove all download tasks for this url as it would be pointless work.
-  tasks_.erase(
-      std::remove(tasks_.begin(), tasks_.end(), std::make_pair(DOWNLOAD, url)),
-      tasks_.end());
+  CancelDownloadOfflineURL(url);
   tasks_.push_back(std::make_pair(DELETE, url));
   HandleNextTask();
 }
@@ -65,6 +63,12 @@ void URLDownloader::DownloadOfflineURL(const GURL& url) {
   }
 }
 
+void URLDownloader::CancelDownloadOfflineURL(const GURL& url) {
+  tasks_.erase(
+      std::remove(tasks_.begin(), tasks_.end(), std::make_pair(DOWNLOAD, url)),
+      tasks_.end());
+}
+
 void URLDownloader::DownloadCompletionHandler(const GURL& url,
                                               const std::string& title,
                                               SuccessState success) {

ios/chrome/browser/reading_list/url_downloader.h

@@ -68,6 +68,9 @@ class URLDownloader {
   // Asynchronously download an offline version of the URL.
   void DownloadOfflineURL(const GURL& url);
 
+  // Cancels the download job an offline version of the URL.
+  void CancelDownloadOfflineURL(const GURL& url);
+
   // Asynchronously remove the offline version of the URL if it exists.
   void RemoveOfflineURL(const GURL& url);