Rename Toolkit's webextensions component directory to better reflect what it is.

1 files changed, 799 insertions, 0 deletions

diff --git a/toolkit/components/webextensions/ext-downloads.js b/toolkit/components/webextensions/ext-downloads.js
new file mode 100644
index 000000000..132814ae4
--- /dev/null
+++ b/toolkit/components/webextensions/ext-downloads.js
@@ -0,0 +1,799 @@
+"use strict";
+
+var {classes: Cc, interfaces: Ci, utils: Cu} = Components;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+
+XPCOMUtils.defineLazyModuleGetter(this, "Downloads",
+                                  "resource://gre/modules/Downloads.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "DownloadPaths",
+                                  "resource://gre/modules/DownloadPaths.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "OS",
+                                  "resource://gre/modules/osfile.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
+                                  "resource://gre/modules/FileUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
+                                  "resource://gre/modules/NetUtil.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "EventEmitter",
+                                  "resource://devtools/shared/event-emitter.js");
+
+Cu.import("resource://gre/modules/ExtensionUtils.jsm");
+const {
+  ignoreEvent,
+  normalizeTime,
+  runSafeSync,
+  SingletonEventManager,
+  PlatformInfo,
+} = ExtensionUtils;
+
+const DOWNLOAD_ITEM_FIELDS = ["id", "url", "referrer", "filename", "incognito",
+                              "danger", "mime", "startTime", "endTime",
+                              "estimatedEndTime", "state",
+                              "paused", "canResume", "error",
+                              "bytesReceived", "totalBytes",
+                              "fileSize", "exists",
+                              "byExtensionId", "byExtensionName"];
+
+// Fields that we generate onChanged events for.
+const DOWNLOAD_ITEM_CHANGE_FIELDS = ["endTime", "state", "paused", "canResume",
+                                     "error", "exists"];
+
+// From https://fetch.spec.whatwg.org/#forbidden-header-name
+const FORBIDDEN_HEADERS = ["ACCEPT-CHARSET", "ACCEPT-ENCODING",
+  "ACCESS-CONTROL-REQUEST-HEADERS", "ACCESS-CONTROL-REQUEST-METHOD",
+  "CONNECTION", "CONTENT-LENGTH", "COOKIE", "COOKIE2", "DATE", "DNT",
+  "EXPECT", "HOST", "KEEP-ALIVE", "ORIGIN", "REFERER", "TE", "TRAILER",
+  "TRANSFER-ENCODING", "UPGRADE", "VIA"];
+
+const FORBIDDEN_PREFIXES = /^PROXY-|^SEC-/i;
+
+class DownloadItem {
+  constructor(id, download, extension) {
+    this.id = id;
+    this.download = download;
+    this.extension = extension;
+    this.prechange = {};
+  }
+
+  get url() { return this.download.source.url; }
+  get referrer() { return this.download.source.referrer; }
+  get filename() { return this.download.target.path; }
+  get incognito() { return this.download.source.isPrivate; }
+  get danger() { return "safe"; } // TODO
+  get mime() { return this.download.contentType; }
+  get startTime() { return this.download.startTime; }
+  get endTime() { return null; } // TODO
+  get estimatedEndTime() { return null; } // TODO
+  get state() {
+    if (this.download.succeeded) {
+      return "complete";
+    }
+    if (this.download.canceled) {
+      return "interrupted";
+    }
+    return "in_progress";
+  }
+  get paused() {
+    return this.download.canceled && this.download.hasPartialData && !this.download.error;
+  }
+  get canResume() {
+    return (this.download.stopped || this.download.canceled) &&
+      this.download.hasPartialData && !this.download.error;
+  }
+  get error() {
+    if (!this.download.stopped || this.download.succeeded) {
+      return null;
+    }
+    // TODO store this instead of calculating it
+
+    if (this.download.error) {
+      if (this.download.error.becauseSourceFailed) {
+        return "NETWORK_FAILED"; // TODO
+      }
+      if (this.download.error.becauseTargetFailed) {
+        return "FILE_FAILED"; // TODO
+      }
+      return "CRASH";
+    }
+    return "USER_CANCELED";
+  }
+  get bytesReceived() {
+    return this.download.currentBytes;
+  }
+  get totalBytes() {
+    return this.download.hasProgress ? this.download.totalBytes : -1;
+  }
+  get fileSize() {
+    // todo: this is supposed to be post-compression
+    return this.download.succeeded ? this.download.target.size : -1;
+  }
+  get exists() { return this.download.target.exists; }
+  get byExtensionId() { return this.extension ? this.extension.id : undefined; }
+  get byExtensionName() { return this.extension ? this.extension.name : undefined; }
+
+  /**
+   * Create a cloneable version of this object by pulling all the
+   * fields into simple properties (instead of getters).
+   *
+   * @returns {object} A DownloadItem with flat properties,
+   *                   suitable for cloning.
+   */
+  serialize() {
+    let obj = {};
+    for (let field of DOWNLOAD_ITEM_FIELDS) {
+      obj[field] = this[field];
+    }
+    if (obj.startTime) {
+      obj.startTime = obj.startTime.toISOString();
+    }
+    return obj;
+  }
+
+  // When a change event fires, handlers can look at how an individual
+  // field changed by comparing item.fieldname with item.prechange.fieldname.
+  // After all handlers have been invoked, this gets called to store the
+  // current values of all fields ahead of the next event.
+  _change() {
+    for (let field of DOWNLOAD_ITEM_CHANGE_FIELDS) {
+      this.prechange[field] = this[field];
+    }
+  }
+}
+
+
+// DownloadMap maps back and forth betwen the numeric identifiers used in
+// the downloads WebExtension API and a Download object from the Downloads jsm.
+// todo: make id and extension info persistent (bug 1247794)
+const DownloadMap = {
+  currentId: 0,
+  loadPromise: null,
+
+  // Maps numeric id -> DownloadItem
+  byId: new Map(),
+
+  // Maps Download object -> DownloadItem
+  byDownload: new WeakMap(),
+
+  lazyInit() {
+    if (this.loadPromise == null) {
+      EventEmitter.decorate(this);
+      this.loadPromise = Downloads.getList(Downloads.ALL).then(list => {
+        let self = this;
+        return list.addView({
+          onDownloadAdded(download) {
+            const item = self.newFromDownload(download, null);
+            self.emit("create", item);
+          },
+
+          onDownloadRemoved(download) {
+            const item = self.byDownload.get(download);
+            if (item != null) {
+              self.emit("erase", item);
+              self.byDownload.delete(download);
+              self.byId.delete(item.id);
+            }
+          },
+
+          onDownloadChanged(download) {
+            const item = self.byDownload.get(download);
+            if (item == null) {
+              Cu.reportError("Got onDownloadChanged for unknown download object");
+            } else {
+              // We get the first one of these when the download is started.
+              // In this case, don't emit anything, just initialize prechange.
+              if (Object.keys(item.prechange).length > 0) {
+                self.emit("change", item);
+              }
+              item._change();
+            }
+          },
+        }).then(() => list.getAll())
+          .then(downloads => {
+            downloads.forEach(download => {
+              this.newFromDownload(download, null);
+            });
+          })
+          .then(() => list);
+      });
+    }
+    return this.loadPromise;
+  },
+
+  getDownloadList() {
+    return this.lazyInit();
+  },
+
+  getAll() {
+    return this.lazyInit().then(() => this.byId.values());
+  },
+
+  fromId(id) {
+    const download = this.byId.get(id);
+    if (!download) {
+      throw new Error(`Invalid download id ${id}`);
+    }
+    return download;
+  },
+
+  newFromDownload(download, extension) {
+    if (this.byDownload.has(download)) {
+      return this.byDownload.get(download);
+    }
+
+    const id = ++this.currentId;
+    let item = new DownloadItem(id, download, extension);
+    this.byId.set(id, item);
+    this.byDownload.set(download, item);
+    return item;
+  },
+
+  erase(item) {
+    // This will need to get more complicated for bug 1255507 but for now we
+    // only work with downloads in the DownloadList from getAll()
+    return this.getDownloadList().then(list => {
+      list.remove(item.download);
+    });
+  },
+};
+
+// Create a callable function that filters a DownloadItem based on a
+// query object of the type passed to search() or erase().
+function downloadQuery(query) {
+  let queryTerms = [];
+  let queryNegativeTerms = [];
+  if (query.query != null) {
+    for (let term of query.query) {
+      if (term[0] == "-") {
+        queryNegativeTerms.push(term.slice(1).toLowerCase());
+      } else {
+        queryTerms.push(term.toLowerCase());
+      }
+    }
+  }
+
+  function normalizeDownloadTime(arg, before) {
+    if (arg == null) {
+      return before ? Number.MAX_VALUE : 0;
+    }
+    return normalizeTime(arg).getTime();
+  }
+
+  const startedBefore = normalizeDownloadTime(query.startedBefore, true);
+  const startedAfter = normalizeDownloadTime(query.startedAfter, false);
+  // const endedBefore = normalizeDownloadTime(query.endedBefore, true);
+  // const endedAfter = normalizeDownloadTime(query.endedAfter, false);
+
+  const totalBytesGreater = query.totalBytesGreater || 0;
+  const totalBytesLess = (query.totalBytesLess != null)
+        ? query.totalBytesLess : Number.MAX_VALUE;
+
+  // Handle options for which we can have a regular expression and/or
+  // an explicit value to match.
+  function makeMatch(regex, value, field) {
+    if (value == null && regex == null) {
+      return input => true;
+    }
+
+    let re;
+    try {
+      re = new RegExp(regex || "", "i");
+    } catch (err) {
+      throw new Error(`Invalid ${field}Regex: ${err.message}`);
+    }
+    if (value == null) {
+      return input => re.test(input);
+    }
+
+    value = value.toLowerCase();
+    if (re.test(value)) {
+      return input => (value == input);
+    }
+    return input => false;
+  }
+
+  const matchFilename = makeMatch(query.filenameRegex, query.filename, "filename");
+  const matchUrl = makeMatch(query.urlRegex, query.url, "url");
+
+  return function(item) {
+    const url = item.url.toLowerCase();
+    const filename = item.filename.toLowerCase();
+
+    if (!queryTerms.every(term => url.includes(term) || filename.includes(term))) {
+      return false;
+    }
+
+    if (queryNegativeTerms.some(term => url.includes(term) || filename.includes(term))) {
+      return false;
+    }
+
+    if (!matchFilename(filename) || !matchUrl(url)) {
+      return false;
+    }
+
+    if (!item.startTime) {
+      if (query.startedBefore != null || query.startedAfter != null) {
+        return false;
+      }
+    } else if (item.startTime > startedBefore || item.startTime < startedAfter) {
+      return false;
+    }
+
+    // todo endedBefore, endedAfter
+
+    if (item.totalBytes == -1) {
+      if (query.totalBytesGreater != null || query.totalBytesLess != null) {
+        return false;
+      }
+    } else if (item.totalBytes <= totalBytesGreater || item.totalBytes >= totalBytesLess) {
+      return false;
+    }
+
+    // todo: include danger
+    const SIMPLE_ITEMS = ["id", "mime", "startTime", "endTime", "state",
+                          "paused", "error",
+                          "bytesReceived", "totalBytes", "fileSize", "exists"];
+    for (let field of SIMPLE_ITEMS) {
+      if (query[field] != null && item[field] != query[field]) {
+        return false;
+      }
+    }
+
+    return true;
+  };
+}
+
+function queryHelper(query) {
+  let matchFn;
+  try {
+    matchFn = downloadQuery(query);
+  } catch (err) {
+    return Promise.reject({message: err.message});
+  }
+
+  let compareFn;
+  if (query.orderBy != null) {
+    const fields = query.orderBy.map(field => field[0] == "-"
+                                     ? {reverse: true, name: field.slice(1)}
+                                     : {reverse: false, name: field});
+
+    for (let field of fields) {
+      if (!DOWNLOAD_ITEM_FIELDS.includes(field.name)) {
+        return Promise.reject({message: `Invalid orderBy field ${field.name}`});
+      }
+    }
+
+    compareFn = (dl1, dl2) => {
+      for (let field of fields) {
+        const val1 = dl1[field.name];
+        const val2 = dl2[field.name];
+
+        if (val1 < val2) {
+          return field.reverse ? 1 : -1;
+        } else if (val1 > val2) {
+          return field.reverse ? -1 : 1;
+        }
+      }
+      return 0;
+    };
+  }
+
+  return DownloadMap.getAll().then(downloads => {
+    if (compareFn) {
+      downloads = Array.from(downloads);
+      downloads.sort(compareFn);
+    }
+    let results = [];
+    for (let download of downloads) {
+      if (query.limit && results.length >= query.limit) {
+        break;
+      }
+      if (matchFn(download)) {
+        results.push(download);
+      }
+    }
+    return results;
+  });
+}
+
+extensions.registerSchemaAPI("downloads", "addon_parent", context => {
+  let {extension} = context;
+  return {
+    downloads: {
+      download(options) {
+        let {filename} = options;
+        if (filename && PlatformInfo.os === "win") {
+          // cross platform javascript code uses "/"
+          filename = filename.replace(/\//g, "\\");
+        }
+
+        if (filename != null) {
+          if (filename.length == 0) {
+            return Promise.reject({message: "filename must not be empty"});
+          }
+
+          let path = OS.Path.split(filename);
+          if (path.absolute) {
+            return Promise.reject({message: "filename must not be an absolute path"});
+          }
+
+          if (path.components.some(component => component == "..")) {
+            return Promise.reject({message: "filename must not contain back-references (..)"});
+          }
+        }
+
+        if (options.conflictAction == "prompt") {
+          // TODO
+          return Promise.reject({message: "conflictAction prompt not yet implemented"});
+        }
+
+        if (options.headers) {
+          for (let {name} of options.headers) {
+            if (FORBIDDEN_HEADERS.includes(name.toUpperCase()) || name.match(FORBIDDEN_PREFIXES)) {
+              return Promise.reject({message: "Forbidden request header name"});
+            }
+          }
+        }
+
+        // Handle method, headers and body options.
+        function adjustChannel(channel) {
+          if (channel instanceof Ci.nsIHttpChannel) {
+            const method = options.method || "GET";
+            channel.requestMethod = method;
+
+            if (options.headers) {
+              for (let {name, value} of options.headers) {
+                channel.setRequestHeader(name, value, false);
+              }
+            }
+
+            if (options.body != null) {
+              const stream = Cc["@mozilla.org/io/string-input-stream;1"]
+                             .createInstance(Ci.nsIStringInputStream);
+              stream.setData(options.body, options.body.length);
+
+              channel.QueryInterface(Ci.nsIUploadChannel2);
+              channel.explicitSetUploadStream(stream, null, -1, method, false);
+            }
+          }
+          return Promise.resolve();
+        }
+
+        function createTarget(downloadsDir) {
+          let target;
+          if (filename) {
+            target = OS.Path.join(downloadsDir, filename);
+          } else {
+            let uri = NetUtil.newURI(options.url);
+
+            let remote = "download";
+            if (uri instanceof Ci.nsIURL) {
+              remote = uri.fileName;
+            }
+            target = OS.Path.join(downloadsDir, remote);
+          }
+
+          // Create any needed subdirectories if required by filename.
+          const dir = OS.Path.dirname(target);
+          return OS.File.makeDir(dir, {from: downloadsDir}).then(() => {
+            return OS.File.exists(target);
+          }).then(exists => {
+            // This has a race, something else could come along and create
+            // the file between this test and them time the download code
+            // creates the target file.  But we can't easily fix it without
+            // modifying DownloadCore so we live with it for now.
+            if (exists) {
+              switch (options.conflictAction) {
+                case "uniquify":
+                default:
+                  target = DownloadPaths.createNiceUniqueFile(new FileUtils.File(target)).path;
+                  break;
+
+                case "overwrite":
+                  break;
+              }
+            }
+          }).then(() => {
+            if (!options.saveAs) {
+              return Promise.resolve(target);
+            }
+
+            // Setup the file picker Save As dialog.
+            const picker = Cc["@mozilla.org/filepicker;1"].createInstance(Ci.nsIFilePicker);
+            const window = Services.wm.getMostRecentWindow("navigator:browser");
+            picker.init(window, null, Ci.nsIFilePicker.modeSave);
+            picker.displayDirectory = new FileUtils.File(dir);
+            picker.appendFilters(Ci.nsIFilePicker.filterAll);
+            picker.defaultString = OS.Path.basename(target);
+
+            // Open the dialog and resolve/reject with the result.
+            return new Promise((resolve, reject) => {
+              picker.open(result => {
+                if (result === Ci.nsIFilePicker.returnCancel) {
+                  reject({message: "Download canceled by the user"});
+                } else {
+                  resolve(picker.file.path);
+                }
+              });
+            });
+          });
+        }
+
+        let download;
+        return Downloads.getPreferredDownloadsDirectory()
+          .then(downloadsDir => createTarget(downloadsDir))
+          .then(target => {
+            const source = {
+              url: options.url,
+            };
+
+            if (options.method || options.headers || options.body) {
+              source.adjustChannel = adjustChannel;
+            }
+
+            return Downloads.createDownload({
+              source,
+              target: {
+                path: target,
+                partFilePath: target + ".part",
+              },
+            });
+          }).then(dl => {
+            download = dl;
+            return DownloadMap.getDownloadList();
+          }).then(list => {
+            list.add(download);
+
+            // This is necessary to make pause/resume work.
+            download.tryToKeepPartialData = true;
+            download.start();
+
+            const item = DownloadMap.newFromDownload(download, extension);
+            return item.id;
+          });
+      },
+
+      removeFile(id) {
+        return DownloadMap.lazyInit().then(() => {
+          let item;
+          try {
+            item = DownloadMap.fromId(id);
+          } catch (err) {
+            return Promise.reject({message: `Invalid download id ${id}`});
+          }
+          if (item.state !== "complete") {
+            return Promise.reject({message: `Cannot remove incomplete download id ${id}`});
+          }
+          return OS.File.remove(item.filename, {ignoreAbsent: false}).catch((err) => {
+            return Promise.reject({message: `Could not remove download id ${item.id} because the file doesn't exist`});
+          });
+        });
+      },
+
+      search(query) {
+        return queryHelper(query)
+          .then(items => items.map(item => item.serialize()));
+      },
+
+      pause(id) {
+        return DownloadMap.lazyInit().then(() => {
+          let item;
+          try {
+            item = DownloadMap.fromId(id);
+          } catch (err) {
+            return Promise.reject({message: `Invalid download id ${id}`});
+          }
+          if (item.state != "in_progress") {
+            return Promise.reject({message: `Download ${id} cannot be paused since it is in state ${item.state}`});
+          }
+
+          return item.download.cancel();
+        });
+      },
+
+      resume(id) {
+        return DownloadMap.lazyInit().then(() => {
+          let item;
+          try {
+            item = DownloadMap.fromId(id);
+          } catch (err) {
+            return Promise.reject({message: `Invalid download id ${id}`});
+          }
+          if (!item.canResume) {
+            return Promise.reject({message: `Download ${id} cannot be resumed`});
+          }
+
+          return item.download.start();
+        });
+      },
+
+      cancel(id) {
+        return DownloadMap.lazyInit().then(() => {
+          let item;
+          try {
+            item = DownloadMap.fromId(id);
+          } catch (err) {
+            return Promise.reject({message: `Invalid download id ${id}`});
+          }
+          if (item.download.succeeded) {
+            return Promise.reject({message: `Download ${id} is already complete`});
+          }
+          return item.download.finalize(true);
+        });
+      },
+
+      showDefaultFolder() {
+        Downloads.getPreferredDownloadsDirectory().then(dir => {
+          let dirobj = new FileUtils.File(dir);
+          if (dirobj.isDirectory()) {
+            dirobj.launch();
+          } else {
+            throw new Error(`Download directory ${dirobj.path} is not actually a directory`);
+          }
+        }).catch(Cu.reportError);
+      },
+
+      erase(query) {
+        return queryHelper(query).then(items => {
+          let results = [];
+          let promises = [];
+          for (let item of items) {
+            promises.push(DownloadMap.erase(item));
+            results.push(item.id);
+          }
+          return Promise.all(promises).then(() => results);
+        });
+      },
+
+      open(downloadId) {
+        return DownloadMap.lazyInit().then(() => {
+          let download = DownloadMap.fromId(downloadId).download;
+          if (download.succeeded) {
+            return download.launch();
+          }
+          return Promise.reject({message: "Download has not completed."});
+        }).catch((error) => {
+          return Promise.reject({message: error.message});
+        });
+      },
+
+      show(downloadId) {
+        return DownloadMap.lazyInit().then(() => {
+          let download = DownloadMap.fromId(downloadId);
+          return download.download.showContainingDirectory();
+        }).then(() => {
+          return true;
+        }).catch(error => {
+          return Promise.reject({message: error.message});
+        });
+      },
+
+      getFileIcon(downloadId, options) {
+        return DownloadMap.lazyInit().then(() => {
+          let size = options && options.size ? options.size : 32;
+          let download = DownloadMap.fromId(downloadId).download;
+          let pathPrefix = "";
+          let path;
+
+          if (download.succeeded) {
+            let file = FileUtils.File(download.target.path);
+            path = Services.io.newFileURI(file).spec;
+          } else {
+            path = OS.Path.basename(download.target.path);
+            pathPrefix = "//";
+          }
+
+          return new Promise((resolve, reject) => {
+            let chromeWebNav = Services.appShell.createWindowlessBrowser(true);
+            chromeWebNav
+              .QueryInterface(Ci.nsIInterfaceRequestor)
+              .getInterface(Ci.nsIDocShell)
+              .createAboutBlankContentViewer(Services.scriptSecurityManager.getSystemPrincipal());
+
+            let img = chromeWebNav.document.createElement("img");
+            img.width = size;
+            img.height = size;
+
+            let handleLoad;
+            let handleError;
+            const cleanup = () => {
+              img.removeEventListener("load", handleLoad);
+              img.removeEventListener("error", handleError);
+              chromeWebNav.close();
+              chromeWebNav = null;
+            };
+
+            handleLoad = () => {
+              let canvas = chromeWebNav.document.createElement("canvas");
+              canvas.width = size;
+              canvas.height = size;
+              let context = canvas.getContext("2d");
+              context.drawImage(img, 0, 0, size, size);
+              let dataURL = canvas.toDataURL("image/png");
+              cleanup();
+              resolve(dataURL);
+            };
+
+            handleError = (error) => {
+              Cu.reportError(error);
+              cleanup();
+              reject(new Error("An unexpected error occurred"));
+            };
+
+            img.addEventListener("load", handleLoad);
+            img.addEventListener("error", handleError);
+            img.src = `moz-icon:${pathPrefix}${path}?size=${size}`;
+          });
+        }).catch((error) => {
+          return Promise.reject({message: error.message});
+        });
+      },
+
+      // When we do setShelfEnabled(), check for additional "downloads.shelf" permission.
+      // i.e.:
+      // setShelfEnabled(enabled) {
+      //   if (!extension.hasPermission("downloads.shelf")) {
+      //     throw new context.cloneScope.Error("Permission denied because 'downloads.shelf' permission is missing.");
+      //   }
+      //   ...
+      // }
+
+      onChanged: new SingletonEventManager(context, "downloads.onChanged", fire => {
+        const handler = (what, item) => {
+          let changes = {};
+          const noundef = val => (val === undefined) ? null : val;
+          DOWNLOAD_ITEM_CHANGE_FIELDS.forEach(fld => {
+            if (item[fld] != item.prechange[fld]) {
+              changes[fld] = {
+                previous: noundef(item.prechange[fld]),
+                current: noundef(item[fld]),
+              };
+            }
+          });
+          if (Object.keys(changes).length > 0) {
+            changes.id = item.id;
+            runSafeSync(context, fire, changes);
+          }
+        };
+
+        let registerPromise = DownloadMap.getDownloadList().then(() => {
+          DownloadMap.on("change", handler);
+        });
+        return () => {
+          registerPromise.then(() => {
+            DownloadMap.off("change", handler);
+          });
+        };
+      }).api(),
+
+      onCreated: new SingletonEventManager(context, "downloads.onCreated", fire => {
+        const handler = (what, item) => {
+          runSafeSync(context, fire, item.serialize());
+        };
+        let registerPromise = DownloadMap.getDownloadList().then(() => {
+          DownloadMap.on("create", handler);
+        });
+        return () => {
+          registerPromise.then(() => {
+            DownloadMap.off("create", handler);
+          });
+        };
+      }).api(),
+
+      onErased: new SingletonEventManager(context, "downloads.onErased", fire => {
+        const handler = (what, item) => {
+          runSafeSync(context, fire, item.id);
+        };
+        let registerPromise = DownloadMap.getDownloadList().then(() => {
+          DownloadMap.on("erase", handler);
+        });
+        return () => {
+          registerPromise.then(() => {
+            DownloadMap.off("erase", handler);
+          });
+        };
+      }).api(),
+
+      onDeterminingFilename: ignoreEvent(context, "downloads.onDeterminingFilename"),
+    },
+  };
+});