MD Downloads: track downloads in C++, dispatch discrete JS updates

chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.cc

Index: chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.cc
diff --git a/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.cc b/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.cc
index 403cbbf3ca063f06b9ae59dbd7a9447482af0352..39d3cc3f462c678aebfff654073563253d9166aa 100644
--- a/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.cc
+++ b/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.cc
@@ -11,10 +11,7 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/i18n/rtl.h"
-#include "base/i18n/time_formatting.h"
 #include "base/logging.h"
-#include "base/memory/singleton.h"
-#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_number_conversions.h"
@@ -22,10 +19,8 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/supports_user_data.h"
 #include "base/threading/thread.h"
-#include "base/value_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
-#include "chrome/browser/download/download_crx_util.h"
 #include "chrome/browser/download/download_danger_prompt.h"
 #include "chrome/browser/download/download_history.h"
 #include "chrome/browser/download/download_item_model.h"
@@ -34,8 +29,6 @@
 #include "chrome/browser/download/download_service.h"
 #include "chrome/browser/download/download_service_factory.h"
 #include "chrome/browser/download/drag_download_item.h"
-#include "chrome/browser/extensions/api/downloads/downloads_api.h"
-#include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/fileicon_source.h"
@@ -44,26 +37,20 @@
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/download_item.h"
+#include "content/public/browser/download_manager.h"
 #include "content/public/browser/url_data_source.h"
 #include "content/public/browser/user_metrics.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui.h"
-#include "extensions/browser/extension_system.h"
 #include "net/base/filename_util.h"
-#include "third_party/icu/source/i18n/unicode/datefmt.h"
 #include "ui/base/l10n/time_format.h"
 #include "ui/gfx/image/image.h"
 
 using base::UserMetricsAction;
-using content::BrowserContext;
 using content::BrowserThread;
 
 namespace {
 
-// Maximum number of downloads to show. TODO(glen): Remove this and instead
-// stuff the downloads down the pipe slowly.
-size_t kMaxNumberOfDownloads = 150;
-
 enum DownloadsDOMEvent {
   DOWNLOADS_DOM_EVENT_GET_DOWNLOADS = 0,
   DOWNLOADS_DOM_EVENT_OPEN_FILE = 1,
@@ -86,203 +73,11 @@ void CountDownloadsDOMEvents(DownloadsDOMEvent event) {
                             DOWNLOADS_DOM_EVENT_MAX);
 }
 
-// Returns a string constant to be used as the |danger_type| value in
-// CreateDownloadItemValue().  Only return strings for DANGEROUS_FILE,
-// DANGEROUS_URL, DANGEROUS_CONTENT, and UNCOMMON_CONTENT because the
-// |danger_type| value is only defined if the value of |state| is |DANGEROUS|.
-const char* GetDangerTypeString(content::DownloadDangerType danger_type) {
-  switch (danger_type) {
-    case content::DOWNLOAD_DANGER_TYPE_DANGEROUS_FILE:
-      return "DANGEROUS_FILE";
-    case content::DOWNLOAD_DANGER_TYPE_DANGEROUS_URL:
-      return "DANGEROUS_URL";
-    case content::DOWNLOAD_DANGER_TYPE_DANGEROUS_CONTENT:
-      return "DANGEROUS_CONTENT";
-    case content::DOWNLOAD_DANGER_TYPE_UNCOMMON_CONTENT:
-      return "UNCOMMON_CONTENT";
-    case content::DOWNLOAD_DANGER_TYPE_DANGEROUS_HOST:
-      return "DANGEROUS_HOST";
-    case content::DOWNLOAD_DANGER_TYPE_POTENTIALLY_UNWANTED:
-      return "POTENTIALLY_UNWANTED";
-    default:
-      // Don't return a danger type string if it is NOT_DANGEROUS or
-      // MAYBE_DANGEROUS_CONTENT.
-      NOTREACHED();
-      return "";
-  }
-}
-
-// TODO(dbeam): if useful elsewhere, move to base/i18n/time_formatting.h?
-base::string16 TimeFormatLongDate(const base::Time& time) {
-  scoped_ptr<icu::DateFormat> formatter(
-      icu::DateFormat::createDateInstance(icu::DateFormat::kLong));
-  icu::UnicodeString date_string;
-  formatter->format(static_cast<UDate>(time.ToDoubleT() * 1000), date_string);
-  return base::string16(date_string.getBuffer(),
-                        static_cast<size_t>(date_string.length()));
-}
-
-// Returns a JSON dictionary containing some of the attributes of |download|.
-// The JSON dictionary will also have a field "id" set to |id|, and a field
-// "otr" set to |incognito|.
-base::DictionaryValue* CreateDownloadItemValue(
-    content::DownloadItem* download_item,
-    bool incognito) {
-  // TODO(asanka): Move towards using download_model here for getting status and
-  // progress. The difference currently only matters to Drive downloads and
-  // those don't show up on the downloads page, but should.
-  DownloadItemModel download_model(download_item);
-
-  // The items which are to be written into file_value are also described in
-  // chrome/browser/resources/downloads/downloads.js in @typedef for
-  // BackendDownloadObject. Please update it whenever you add or remove
-  // any keys in file_value.
-  base::DictionaryValue* file_value = new base::DictionaryValue();
-
-  file_value->SetInteger(
-      "started", static_cast<int>(download_item->GetStartTime().ToTimeT()));
-  file_value->SetString(
-      "since_string", ui::TimeFormat::RelativeDate(
-          download_item->GetStartTime(), NULL));
-
-  base::Time start_time = download_item->GetStartTime();
-  base::string16 date_string = TimeFormatLongDate(start_time);
-  file_value->SetString("date_string", date_string);
-
-  file_value->SetString("id", base::Uint64ToString(download_item->GetId()));
-
-  base::FilePath download_path(download_item->GetTargetFilePath());
-  file_value->Set("file_path", base::CreateFilePathValue(download_path));
-  file_value->SetString("file_url",
-                        net::FilePathToFileURL(download_path).spec());
-
-  extensions::DownloadedByExtension* by_ext =
-      extensions::DownloadedByExtension::Get(download_item);
-  std::string by_ext_id;
-  std::string by_ext_name;
-  if (by_ext) {
-    by_ext_id = by_ext->id();
-    // TODO(dbeam): why doesn't DownloadsByExtension::name() return a string16?
-    by_ext_name = by_ext->name();
-
-    // Lookup the extension's current name() in case the user changed their
-    // language. This won't work if the extension was uninstalled, so the name
-    // might be the wrong language.
-    bool include_disabled = true;
-    const extensions::Extension* extension = extensions::ExtensionSystem::Get(
-        Profile::FromBrowserContext(download_item->GetBrowserContext()))->
-      extension_service()->GetExtensionById(by_ext->id(), include_disabled);
-    if (extension)
-      file_value->SetString("by_ext_name", extension->name());
-  }
-  file_value->SetString("by_ext_id", by_ext_id);
-  file_value->SetString("by_ext_name", by_ext_name);
-
-  // Keep file names as LTR.
-  base::string16 file_name =
-    download_item->GetFileNameToReportUser().LossyDisplayName();
-  file_name = base::i18n::GetDisplayStringInLTRDirectionality(file_name);
-  file_value->SetString("file_name", file_name);
-  file_value->SetString("url", download_item->GetURL().spec());
-  file_value->SetBoolean("otr", incognito);
-  file_value->SetInteger("total", static_cast<int>(
-      download_item->GetTotalBytes()));
-  file_value->SetBoolean("file_externally_removed",
-                         download_item->GetFileExternallyRemoved());
-  file_value->SetBoolean("resume", download_item->CanResume());
-
-  const char* danger_type = "";
-  base::string16 last_reason_text;
-  // -2 is invalid, -1 means indeterminate, and 0-100 are in-progress.
-  int percent = -2;
-  base::string16 progress_status_text;
-  bool retry = false;
-  const char* state = nullptr;
-
-  switch (download_item->GetState()) {
-    case content::DownloadItem::IN_PROGRESS: {
-      if (download_item->IsDangerous()) {
-        state = "DANGEROUS";
-        // These are the only danger states that the UI is equipped to handle.
-        DCHECK(download_item->GetDangerType() ==
-                   content::DOWNLOAD_DANGER_TYPE_DANGEROUS_FILE ||
-               download_item->GetDangerType() ==
-                   content::DOWNLOAD_DANGER_TYPE_DANGEROUS_URL ||
-               download_item->GetDangerType() ==
-                   content::DOWNLOAD_DANGER_TYPE_DANGEROUS_CONTENT ||
-               download_item->GetDangerType() ==
-                   content::DOWNLOAD_DANGER_TYPE_UNCOMMON_CONTENT ||
-               download_item->GetDangerType() ==
-                   content::DOWNLOAD_DANGER_TYPE_DANGEROUS_HOST ||
-               download_item->GetDangerType() ==
-                   content::DOWNLOAD_DANGER_TYPE_POTENTIALLY_UNWANTED);
-        danger_type = GetDangerTypeString(download_item->GetDangerType());
-      } else if (download_item->IsPaused()) {
-        state = "PAUSED";
-      } else {
-        state = "IN_PROGRESS";
-      }
-      progress_status_text = download_model.GetTabProgressStatusText();
-      percent = download_item->PercentComplete();
-      break;
-    }
-
-    case content::DownloadItem::INTERRUPTED:
-      state = "INTERRUPTED";
-      progress_status_text = download_model.GetTabProgressStatusText();
-
-      if (download_item->CanResume())
-        percent = download_item->PercentComplete();
-
-      last_reason_text = download_model.GetInterruptReasonText();
-      if (content::DOWNLOAD_INTERRUPT_REASON_CRASH ==
-          download_item->GetLastReason() && !download_item->CanResume()) {
-        retry = true;
-      }
-      break;
-
-    case content::DownloadItem::CANCELLED:
-      state = "CANCELLED";
-      retry = true;
-      break;
-
-    case content::DownloadItem::COMPLETE:
-      DCHECK(!download_item->IsDangerous());
-      state = "COMPLETE";
-      break;
-
-    case content::DownloadItem::MAX_DOWNLOAD_STATE:
-      NOTREACHED();
-  }
-
-  DCHECK(state);
-
-  file_value->SetString("danger_type", danger_type);
-  file_value->SetString("last_reason_text", last_reason_text);
-  file_value->SetInteger("percent", percent);
-  file_value->SetString("progress_status_text", progress_status_text);
-  file_value->SetBoolean("retry", retry);
-  file_value->SetString("state", state);
-
-  return file_value;
-}
-
-// Filters out extension downloads and downloads that don't have a filename yet.
-bool IsDownloadDisplayable(const content::DownloadItem& item) {
-  return !download_crx_util::IsExtensionDownload(item) &&
-         !item.IsTemporary() &&
-         !item.GetFileNameToReportUser().empty() &&
-         !item.GetTargetFilePath().empty() &&
-         DownloadItemModel(
-             const_cast<content::DownloadItem*>(&item)).ShouldShowInShelf();
-}
-
 }  // namespace
 
 MdDownloadsDOMHandler::MdDownloadsDOMHandler(
-    content::DownloadManager* download_manager)
-    : download_manager_(download_manager),
-      update_scheduled_(false),
+    content::DownloadManager* download_manager, content::WebUI* web_ui)
+    : list_tracker_(download_manager, web_ui),
       weak_ptr_factory_(this) {
   // Create our fileicon data source.
   Profile* profile = Profile::FromBrowserContext(
@@ -338,95 +133,19 @@ void MdDownloadsDOMHandler::RegisterMessages() {
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
-void MdDownloadsDOMHandler::OnDownloadCreated(
-    content::DownloadManager* manager, content::DownloadItem* download_item) {
-  if (IsDownloadDisplayable(*download_item))
-    ScheduleSendCurrentDownloads();
-  else
-    new_downloads_.insert(download_item->GetId());
-}
-
-void MdDownloadsDOMHandler::OnDownloadUpdated(
-    content::DownloadManager* manager,
-    content::DownloadItem* download_item) {
-  if (update_scheduled_)
-    return;
-
-  bool showing_new_item = false;
-
-  if (new_downloads_.count(download_item->GetId())) {
-    // A new download (that the page doesn't know about yet) has been updated.
-    if (!IsDownloadDisplayable(*download_item)) {
-      // Item isn't ready to be displayed yet. Wait until it is.
-      return;
-    }
-
-    new_downloads_.erase(download_item->GetId());
-    showing_new_item = true;
-  }
-
-  if (showing_new_item || DownloadItemModel(download_item).IsBeingRevived() ||
-      !IsDownloadDisplayable(*download_item)) {
-    // A download will be shown or hidden by this update. Resend the list.
-    ScheduleSendCurrentDownloads();
-    return;
-  }
-
-  if (search_terms_ && !search_terms_->empty()) {
-    // Don't CallUpdateItem() if download_item doesn't match
-    // search_terms_.
-    // TODO(benjhayden): Consider splitting MatchesQuery() out to a function.
-    content::DownloadManager::DownloadVector all_items, filtered_items;
-    all_items.push_back(download_item);
-    DownloadQuery query;
-    query.AddFilter(DownloadQuery::FILTER_QUERY, *search_terms_);
-    query.Search(all_items.begin(), all_items.end(), &filtered_items);
-    if (filtered_items.empty())
-      return;
-  }
-
-  DCHECK(manager);
-  scoped_ptr<base::DictionaryValue> item(CreateDownloadItemValue(
-      download_item,
-      original_notifier_ && manager == GetMainNotifierManager()));
-  CallUpdateItem(*item);
-}
-
-void MdDownloadsDOMHandler::OnDownloadRemoved(
-    content::DownloadManager* manager,
-    content::DownloadItem* download_item) {
-  if (!DownloadItemModel(download_item).ShouldShowInShelf())
-    return;
-
-  // This relies on |download_item| being removed from DownloadManager in this
-  // MessageLoop iteration. |download_item| may not have been removed from
-  // DownloadManager when OnDownloadRemoved() is fired, so bounce off the
-  // MessageLoop to give it a chance to be removed. SendCurrentDownloads() looks
-  // at all downloads, and we do not tell it that |download_item| is being
-  // removed. If DownloadManager is ever changed to not immediately remove
-  // |download_item| from its map when OnDownloadRemoved is sent, then
-  // MdDownloadsDOMHandler::OnDownloadRemoved() will need to explicitly tell
-  // SendCurrentDownloads() that |download_item| was removed. A
-  // SupportsUserData::Data would be the correct way to do this.
-  ScheduleSendCurrentDownloads();
+void MdDownloadsDOMHandler::RenderViewReused(
+    content::RenderViewHost* render_view_host) {
+  list_tracker_.Stop();
 }
 
 void MdDownloadsDOMHandler::HandleGetDownloads(const base::ListValue* args) {
   CountDownloadsDOMEvents(DOWNLOADS_DOM_EVENT_GET_DOWNLOADS);
-  search_terms_.reset(args && !args->empty() ? args->DeepCopy() : NULL);
-  ScheduleSendCurrentDownloads();
-
-  if (!main_notifier_) {
-    main_notifier_.reset(new AllDownloadItemNotifier(download_manager_, this));
-
-    Profile* profile = Profile::FromBrowserContext(
-        download_manager_->GetBrowserContext());
-    if (profile->IsOffTheRecord()) {
-      original_notifier_.reset(new AllDownloadItemNotifier(
-          BrowserContext::GetDownloadManager(profile->GetOriginalProfile()),
-          this));
-    }
-  }
+
+  bool terms_changed = list_tracker_.SetSearchTerms(*args);
+  if (terms_changed)
+    list_tracker_.CallClearAll();
+
+  list_tracker_.Start();
 }
 
 void MdDownloadsDOMHandler::HandleOpenFile(const base::ListValue* args) {
@@ -549,12 +268,17 @@ void MdDownloadsDOMHandler::HandleClearAll(const base::ListValue* args) {
 
   CountDownloadsDOMEvents(DOWNLOADS_DOM_EVENT_CLEAR_ALL);
 
+  list_tracker_.CallClearAll();
+  list_tracker_.Stop();
+
   DownloadVector downloads;
   if (GetMainNotifierManager())
     GetMainNotifierManager()->GetAllDownloads(&downloads);
   if (GetOriginalNotifierManager())
     GetOriginalNotifierManager()->GetAllDownloads(&downloads);
   RemoveDownloads(downloads);
+
+  list_tracker_.Start();
 }
 
 void MdDownloadsDOMHandler::RemoveDownloads(const DownloadVector& to_remove) {
@@ -590,29 +314,14 @@ void MdDownloadsDOMHandler::HandleOpenDownloadsFolder(
 
 // MdDownloadsDOMHandler, private: --------------------------------------------
 
-void MdDownloadsDOMHandler::ScheduleSendCurrentDownloads() {
-  // Don't call SendCurrentDownloads() every time anything changes. Batch them
-  // together instead. This may handle hundreds of OnDownloadDestroyed() calls
-  // in a single UI message loop iteration when the user Clears All downloads.
-  if (update_scheduled_)
-    return;
-
-  update_scheduled_ = true;
-
-  BrowserThread::PostTask(
-      BrowserThread::UI, FROM_HERE,
-      base::Bind(&MdDownloadsDOMHandler::SendCurrentDownloads,
-                 weak_ptr_factory_.GetWeakPtr()));
-}
-
 content::DownloadManager* MdDownloadsDOMHandler::GetMainNotifierManager()
     const {
-  return main_notifier_ ? main_notifier_->GetManager() : nullptr;
+  return list_tracker_.GetMainNotifierManager();
 }
 
 content::DownloadManager* MdDownloadsDOMHandler::GetOriginalNotifierManager()
     const {
-  return original_notifier_ ? original_notifier_->GetManager() : nullptr;
+  return list_tracker_.GetOriginalNotifierManager();
 }
 
 void MdDownloadsDOMHandler::FinalizeRemovals() {
@@ -628,37 +337,6 @@ void MdDownloadsDOMHandler::FinalizeRemovals() {
   }
 }
 
-void MdDownloadsDOMHandler::SendCurrentDownloads() {
-  update_scheduled_ = false;
-
-  content::DownloadManager::DownloadVector all_items, filtered_items;
-  if (GetMainNotifierManager()) {
-    GetMainNotifierManager()->GetAllDownloads(&all_items);
-    GetMainNotifierManager()->CheckForHistoryFilesRemoval();
-  }
-  if (GetOriginalNotifierManager()) {
-    GetOriginalNotifierManager()->GetAllDownloads(&all_items);
-    GetOriginalNotifierManager()->CheckForHistoryFilesRemoval();
-  }
-
-  DownloadQuery query;
-  if (search_terms_ && !search_terms_->empty())
-    query.AddFilter(DownloadQuery::FILTER_QUERY, *search_terms_);
-  query.AddFilter(base::Bind(&IsDownloadDisplayable));
-  query.AddSorter(DownloadQuery::SORT_START_TIME, DownloadQuery::DESCENDING);
-  query.Limit(kMaxNumberOfDownloads);
-  query.Search(all_items.begin(), all_items.end(), &filtered_items);
-
-  base::ListValue results_value;
-  for (auto* item : filtered_items) {
-    results_value.Append(CreateDownloadItemValue(
-        item,
-        original_notifier_ && GetMainNotifierManager() &&
-            GetMainNotifierManager()->GetDownload(item->GetId()) == item));
-  }
-  CallUpdateAll(results_value);
-}
-
 void MdDownloadsDOMHandler::ShowDangerPrompt(
     content::DownloadItem* dangerous_item) {
   DownloadDangerPrompt* danger_prompt = DownloadDangerPrompt::Create(
@@ -722,11 +400,3 @@ content::DownloadItem* MdDownloadsDOMHandler::GetDownloadById(uint32 id) {
 content::WebContents* MdDownloadsDOMHandler::GetWebUIWebContents() {
   return web_ui()->GetWebContents();
 }
-
-void MdDownloadsDOMHandler::CallUpdateAll(const base::ListValue& list) {
-  web_ui()->CallJavascriptFunction("downloads.Manager.updateAll", list);
-}
-
-void MdDownloadsDOMHandler::CallUpdateItem(const base::DictionaryValue& item) {
-  web_ui()->CallJavascriptFunction("downloads.Manager.updateItem", item);
-}