--- a/browser/components/downloads/DownloadsCommon.jsm
+++ b/browser/components/downloads/DownloadsCommon.jsm
@@ -86,16 +86,19 @@ const kDownloadsStringsRequiringFormatti
 const kDownloadsStringsRequiringPluralForm = {
   otherDownloads3: true
 };
 
 const kPartialDownloadSuffix = ".part";
 
 const kPrefBranch = Services.prefs.getBranch("browser.download.");
 
+const DESTINATION_FILE_URI_ANNO = "downloads/destinationFileURI";
+const DOWNLOAD_META_DATA_ANNO   = "downloads/metaData";
+
 var PrefObserver = {
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver,
                                          Ci.nsISupportsWeakReference]),
   getPref(name) {
     try {
       switch (typeof this.prefs[name]) {
         case "boolean":
           return kPrefBranch.getBoolPref(name);
@@ -191,16 +194,94 @@ this.DownloadsCommon = {
    * Indicates whether we should show visual notification on the indicator
    * when a download event is triggered.
    */
   get animateNotifications() {
     return PrefObserver.animateNotifications;
   },
 
   /**
+   * This cache exists in order to optimize the load of the Downloads View, when
+   * Places annotations for history downloads must be read. In fact, annotations
+   * are stored in a single table, and reading all of them at once is much more
+   * efficient than an individual query.
+   *
+   * When this property is first requested, it reads the annotations for all the
+   * history downloads and stores them indefinitely.
+   *
+   * The historical annotations are not expected to change for the duration of
+   * the session, except in the case where a session download is running for the
+   * same URI as a history download. To ensure we don't use stale data, URIs
+   * corresponding to session downloads are permanently removed from the cache.
+   * This is a very small mumber compared to history downloads.
+   *
+   * This property returns a Map from each download source URI found in Places
+   * annotations to an object with the format:
+   *
+   * { targetFileSpec, state, endTime, fileSize, ... }
+   *
+   * The targetFileSpec property is the value of "downloads/destinationFileURI",
+   * while the other properties are taken from "downloads/metaData". Any of the
+   * properties may be missing from the object.
+   */
+  get cachedPlacesMetaData() {
+    if (!this._cachedPlacesMetaData) {
+      this._cachedPlacesMetaData = new Map();
+
+      // Read the metadata annotations first, but ignore invalid JSON.
+      for (let result of PlacesUtils.annotations.getAnnotationsWithName(
+                                                 DOWNLOAD_META_DATA_ANNO)) {
+        try {
+          this._cachedPlacesMetaData.set(result.uri.spec,
+                                          JSON.parse(result.annotationValue));
+        } catch (ex) {}
+      }
+
+      // Add the target file annotations to the metadata.
+      for (let result of PlacesUtils.annotations.getAnnotationsWithName(
+                                                 DESTINATION_FILE_URI_ANNO)) {
+        let metaData = this._cachedPlacesMetaData.get(result.uri.spec);
+        if (!metaData) {
+          metaData = {};
+          this._cachedPlacesMetaData.set(result.uri.spec, metaData);
+        }
+        metaData.targetFileSpec = result.annotationValue;
+      }
+    }
+
+    return this._cachedPlacesMetaData;
+  },
+
+  /**
+   * Reads current metadata from Places annotations for the specified URI, and
+   * returns an object with the format:
+   *
+   * { targetFileSpec, state, endTime, fileSize, ... }
+   *
+   * The targetFileSpec property is the value of "downloads/destinationFileURI",
+   * while the other properties are taken from "downloads/metaData". Any of the
+   * properties may be missing from the object.
+   */
+  getPlacesMetaDataFor(spec) {
+    let metaData = {};
+
+    try {
+      let uri = NetUtil.newURI(spec);
+      try {
+        metaData = JSON.parse(PlacesUtils.annotations.getPageAnnotation(
+                                          uri, DOWNLOAD_META_DATA_ANNO));
+      } catch (ex) {}
+      metaData.targetFileSpec = PlacesUtils.annotations.getPageAnnotation(
+                                            uri, DESTINATION_FILE_URI_ANNO);
+    } catch (ex) {}
+
+    return metaData;
+  },
+
+  /**
    * Get access to one of the DownloadsData or PrivateDownloadsData objects,
    * depending on the privacy status of the window in question.
    *
    * @param aWindow
    *        The browser window which owns the download button.
    */
   getData(aWindow) {
     if (PrivateBrowsingUtils.isContentWindowPrivate(aWindow)) {

--- a/browser/components/downloads/DownloadsViewUI.jsm
+++ b/browser/components/downloads/DownloadsViewUI.jsm
@@ -30,19 +30,16 @@ XPCOMUtils.defineLazyModuleGetter(this, 
                                   "resource://gre/modules/NetUtil.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PlacesUtils",
                                   "resource://gre/modules/PlacesUtils.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "RecentWindow",
                                   "resource:///modules/RecentWindow.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "OS",
                                   "resource://gre/modules/osfile.jsm");
 
-const DESTINATION_FILE_URI_ANNO  = "downloads/destinationFileURI";
-const DOWNLOAD_META_DATA_ANNO    = "downloads/metaData";
-
 this.DownloadsViewUI = {
   /**
    * Returns true if the given string is the name of a command that can be
    * handled by the Downloads user interface, including standard commands.
    */
   isCommandName(name) {
     return name.startsWith("cmd_") || name.startsWith("downloadsCmd_");
   },
@@ -57,18 +54,16 @@ this.DownloadsViewUI.BaseDownloadsPlaces
     this.window = window;
 
     // Map download URLs to download element shells regardless of their type
     this._downloadElementsShellsForURI = new Map();
 
     // Map download data items to their element shells.
     this._viewItemsForDownloads = new WeakMap();
 
-    this.__cachedPlacesMetaData = null;
-
     // Points to the last session download element. We keep track of this
    // in order to keep all session downloads above past downloads.
     this._lastSessionDownloadElement = null;
 
     this._searchTerm = "";
 
     this._active = active;
 
@@ -82,94 +77,16 @@ this.DownloadsViewUI.BaseDownloadsPlaces
     DownloadsCommon.getIndicatorData(window).attention = DownloadsCommon.ATTENTION_NONE;
   }
 
   destructor() {
     this._downloadsData.removeView(this);
   }
 
   /**
-   * This cache exists in order to optimize the load of the Downloads View, when
-   * Places annotations for history downloads must be read. In fact, annotations
-   * are stored in a single table, and reading all of them at once is much more
-   * efficient than an individual query.
-   *
-   * When this property is first requested, it reads the annotations for all the
-   * history downloads and stores them indefinitely.
-   *
-   * The historical annotations are not expected to change for the duration of
-   * the session, except in the case where a session download is running for the
-   * same URI as a history download. To ensure we don't use stale data, URIs
-   * corresponding to session downloads are permanently removed from the cache.
-   * This is a very small mumber compared to history downloads.
-   *
-   * This property returns a Map from each download source URI found in Places
-   * annotations to an object with the format:
-   *
-   * { targetFileSpec, state, endTime, fileSize, ... }
-   *
-   * The targetFileSpec property is the value of "downloads/destinationFileURI",
-   * while the other properties are taken from "downloads/metaData". Any of the
-   * properties may be missing from the object.
-   */
-  get _cachedPlacesMetaData() {
-    if (!this.__cachedPlacesMetaData) {
-      this.__cachedPlacesMetaData = new Map();
-
-      // Read the metadata annotations first, but ignore invalid JSON.
-      for (let result of PlacesUtils.annotations.getAnnotationsWithName(
-                                                 DOWNLOAD_META_DATA_ANNO)) {
-        try {
-          this.__cachedPlacesMetaData.set(result.uri.spec,
-                                          JSON.parse(result.annotationValue));
-        } catch (ex) {}
-      }
-
-      // Add the target file annotations to the metadata.
-      for (let result of PlacesUtils.annotations.getAnnotationsWithName(
-                                                 DESTINATION_FILE_URI_ANNO)) {
-        let metaData = this.__cachedPlacesMetaData.get(result.uri.spec);
-        if (!metaData) {
-          metaData = {};
-          this.__cachedPlacesMetaData.set(result.uri.spec, metaData);
-        }
-        metaData.targetFileSpec = result.annotationValue;
-      }
-    }
-
-    return this.__cachedPlacesMetaData;
-  }
-
-  /**
-   * Reads current metadata from Places annotations for the specified URI, and
-   * returns an object with the format:
-   *
-   * { targetFileSpec, state, endTime, fileSize, ... }
-   *
-   * The targetFileSpec property is the value of "downloads/destinationFileURI",
-   * while the other properties are taken from "downloads/metaData". Any of the
-   * properties may be missing from the object.
-   */
-  _getPlacesMetaDataFor(spec) {
-    let metaData = {};
-
-    try {
-      let uri = NetUtil.newURI(spec);
-      try {
-        metaData = JSON.parse(PlacesUtils.annotations.getPageAnnotation(
-                                          uri, DOWNLOAD_META_DATA_ANNO));
-      } catch (ex) {}
-      metaData.targetFileSpec = PlacesUtils.annotations.getPageAnnotation(
-                                            uri, DESTINATION_FILE_URI_ANNO);
-    } catch (ex) {}
-
-    return metaData;
-  }
-
-  /**
    * Given a data item for a session download, or a places node for a past
    * download, updates the view as necessary.
    *  1. If the given data is a places node, we check whether there are any
    *     elements for the same download url. If there are, then we just reset
    *     their places node. Otherwise we add a new download element.
    *  2. If the given data is a data item, we first check if there's a history
    *     download in the list that is not associated with a data item. If we
    *     found one, we use it for the data item as well and reposition it
@@ -205,17 +122,17 @@ this.DownloadsViewUI.BaseDownloadsPlaces
     // stale metadata around for the corresponding history download. This
     // prevents stale state from being used if the view is rebuilt.
     //
     // Note that we will eagerly load the data in the cache at this point, even
     // if we have seen no history download. The case where no history download
     // will appear at all is rare enough in normal usage, so we can apply this
     // simpler solution rather than keeping a list of cache items to ignore.
     if (sessionDownload) {
-      this._cachedPlacesMetaData.delete(sessionDownload.source.url);
+      DownloadsCommon.cachedPlacesMetaData.delete(sessionDownload.source.url);
     }
 
     let newOrUpdatedShell = null;
 
     // Trivial: if there are no shells for this download URI, we always
     // need to create one.
     let shouldCreateShell = shellsForURI.size == 0;
 
@@ -251,18 +168,18 @@ this.DownloadsViewUI.BaseDownloadsPlaces
     }
 
     if (shouldCreateShell) {
       // If we are adding a new history download here, it means there is no
       // associated session download, thus we must read the Places metadata,
       // because it will not be obscured by the session download.
       let historyDownload = null;
       if (aPlacesNode) {
-        let metaData = this._cachedPlacesMetaData.get(aPlacesNode.uri) ||
-                       this._getPlacesMetaDataFor(aPlacesNode.uri);
+        let metaData = DownloadsCommon.cachedPlacesMetaData.get(aPlacesNode.uri) ||
+                       DownloadsCommon.getPlacesMetaDataFor(aPlacesNode.uri);
         historyDownload = new DownloadsViewUI.HistoryDownload(aPlacesNode);
         historyDownload.updateFromMetaData(metaData);
       }
       let shell = new DownloadsViewUI.HistoryDownloadElementShell(sessionDownload,
         historyDownload, this.window, element);
       shell.element._placesNode = aPlacesNode;
       newOrUpdatedShell = shell;
       shellsForURI.add(shell);
@@ -382,17 +299,17 @@ this.DownloadsViewUI.BaseDownloadsPlaces
       }
     } else {
       // We have one download element shell containing both a session download
       // and a history download, and we are now removing the session download.
       // Previously, we did not use the Places metadata because it was obscured
       // by the session download. Since this is no longer the case, we have to
       // read the latest metadata before removing the session download.
       let url = shell.historyDownload.source.url;
-      let metaData = this._getPlacesMetaDataFor(url);
+      let metaData = DownloadsCommon.getPlacesMetaDataFor(url);
       shell.historyDownload.updateFromMetaData(metaData);
       shell.sessionDownload = null;
       // Move it below the session-download items;
       if (this._lastSessionDownloadElement == shell.element) {
         this._lastSessionDownloadElement = shell.element.previousSibling;
       } else {
         let before = null;
         if (this._lastSessionDownloadElement) {