diff -r 000000000000 -r 6474c204b198 dom/settings/SettingsDB.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/settings/SettingsDB.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,205 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+let Cc = Components.classes;
+let Ci = Components.interfaces;
+let Cu = Components.utils;
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/ObjectWrapper.jsm");
+
+this.EXPORTED_SYMBOLS = ["SettingsDB", "SETTINGSDB_NAME", "SETTINGSSTORE_NAME"];
+
+const DEBUG = false;
+function debug(s) {
+  if (DEBUG) dump("-*- SettingsDB: " + s + "\n");
+}
+
+this.SETTINGSDB_NAME = "settings";
+this.SETTINGSDB_VERSION = 3;
+this.SETTINGSSTORE_NAME = "settings";
+
+Cu.import("resource://gre/modules/IndexedDBHelper.jsm");
+Cu.import("resource://gre/modules/FileUtils.jsm");
+Cu.import("resource://gre/modules/NetUtil.jsm");
+
+this.SettingsDB = function SettingsDB() {}
+
+SettingsDB.prototype = {
+
+  __proto__: IndexedDBHelper.prototype,
+
+  upgradeSchema: function upgradeSchema(aTransaction, aDb, aOldVersion, aNewVersion) {
+    let objectStore;
+    if (aOldVersion == 0) {
+      objectStore = aDb.createObjectStore(SETTINGSSTORE_NAME, { keyPath: "settingName" });
+      if (DEBUG) debug("Created object stores");
+    } else if (aOldVersion == 1) {
+      if (DEBUG) debug("Get object store for upgrade and remove old index");
+      objectStore = aTransaction.objectStore(SETTINGSSTORE_NAME);
+      objectStore.deleteIndex("settingValue");
+    } else {
+      if (DEBUG) debug("Get object store for upgrade");
+      objectStore = aTransaction.objectStore(SETTINGSSTORE_NAME);
+    }
+
+    // Loading resource://app/defaults/settings.json doesn't work because
+    // settings.json is not in the omnijar.
+    // So we look for the app dir instead and go from here...
+    let settingsFile = FileUtils.getFile("DefRt", ["settings.json"], false);
+    if (!settingsFile || (settingsFile && !settingsFile.exists())) {
+      // On b2g desktop builds the settings.json file is moved in the
+      // profile directory by the build system.
+      settingsFile = FileUtils.getFile("ProfD", ["settings.json"], false);
+      if (!settingsFile || (settingsFile && !settingsFile.exists())) {
+        return;
+      }
+    }
+
+    let chan = NetUtil.newChannel(settingsFile);
+    let stream = chan.open();
+    // Obtain a converter to read from a UTF-8 encoded input stream.
+    let converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"]
+                    .createInstance(Ci.nsIScriptableUnicodeConverter);
+    converter.charset = "UTF-8";
+    let rawstr = converter.ConvertToUnicode(NetUtil.readInputStreamToString(
+                                            stream,
+                                            stream.available()) || "");
+    let settings;
+    try {
+      settings = JSON.parse(rawstr);
+    } catch(e) {
+      if (DEBUG) debug("Error parsing " + settingsFile.path + " : " + e);
+      return;
+    }
+    stream.close();
+
+    objectStore.openCursor().onsuccess = function(event) {
+      let cursor = event.target.result;
+      if (cursor) {
+        let value = cursor.value;
+        if (value.settingName in settings) {
+          if (DEBUG) debug("Upgrade " +settings[value.settingName]);
+          value.defaultValue = this.prepareValue(settings[value.settingName]);
+          delete settings[value.settingName];
+          if ("settingValue" in value) {
+            value.userValue = this.prepareValue(value.settingValue);
+            delete value.settingValue;
+          }
+          cursor.update(value);
+        } else if ("userValue" in value || "settingValue" in value) {
+          value.defaultValue = undefined;
+          if (aOldVersion == 1 && value.settingValue) {
+            value.userValue = this.prepareValue(value.settingValue);
+            delete value.settingValue;
+          }
+          cursor.update(value);
+        } else {
+          cursor.delete();
+        }
+        cursor.continue();
+      } else {
+        for (let name in settings) {
+          let value = this.prepareValue(settings[name]);
+          if (DEBUG) debug("Set new:" + name +", " + value);
+          objectStore.add({ settingName: name, defaultValue: value, userValue: undefined });
+        }
+      }
+    }.bind(this);
+  },
+
+  // If the value is a data: uri, convert it to a Blob.
+  convertDataURIToBlob: function(aValue) {
+    /* base64 to ArrayBuffer decoding, from
+       https://developer.mozilla.org/en-US/docs/Web/JavaScript/Base64_encoding_and_decoding
+    */
+    function b64ToUint6 (nChr) {
+      return nChr > 64 && nChr < 91 ?
+          nChr - 65
+        : nChr > 96 && nChr < 123 ?
+          nChr - 71
+        : nChr > 47 && nChr < 58 ?
+          nChr + 4
+        : nChr === 43 ?
+          62
+        : nChr === 47 ?
+          63
+        :
+          0;
+    }
+
+    function base64DecToArr(sBase64, nBlocksSize) {
+      let sB64Enc = sBase64.replace(/[^A-Za-z0-9\+\/]/g, ""),
+          nInLen = sB64Enc.length,
+          nOutLen = nBlocksSize ? Math.ceil((nInLen * 3 + 1 >> 2) / nBlocksSize) * nBlocksSize
+                                : nInLen * 3 + 1 >> 2,
+          taBytes = new Uint8Array(nOutLen);
+
+      for (let nMod3, nMod4, nUint24 = 0, nOutIdx = 0, nInIdx = 0; nInIdx < nInLen; nInIdx++) {
+        nMod4 = nInIdx & 3;
+        nUint24 |= b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << 18 - 6 * nMod4;
+        if (nMod4 === 3 || nInLen - nInIdx === 1) {
+          for (nMod3 = 0; nMod3 < 3 && nOutIdx < nOutLen; nMod3++, nOutIdx++) {
+            taBytes[nOutIdx] = nUint24 >>> (16 >>> nMod3 & 24) & 255;
+          }
+          nUint24 = 0;
+        }
+      }
+      return taBytes;
+    }
+
+    // Check if we have a data: uri, and if it's base64 encoded.
+    // data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEA...
+    if (typeof aValue == "string" && aValue.startsWith("data:")) {
+      try {
+        let uri = Services.io.newURI(aValue, null, null);
+        // XXX: that would be nice to reuse the c++ bits of the data:
+        // protocol handler instead.
+        let mimeType = "application/octet-stream";
+        let mimeDelim = aValue.indexOf(";");
+        if (mimeDelim !== -1) {
+          mimeType = aValue.substring(5, mimeDelim);
+        }
+        let start = aValue.indexOf(",") + 1;
+        let isBase64 = ((aValue.indexOf("base64") + 7) == start);
+        let payload = aValue.substring(start);
+
+        return new Blob([isBase64 ? base64DecToArr(payload) : payload],
+                        { type: mimeType });
+      } catch(e) {
+        dump(e);
+      }
+    }
+    return aValue
+  },
+
+  // Makes sure any property that is a data: uri gets converted to a Blob.
+  prepareValue: function(aObject) {
+    let kind = ObjectWrapper.getObjectKind(aObject);
+    if (kind == "array") {
+      let res = [];
+      aObject.forEach(function(aObj) {
+        res.push(this.prepareValue(aObj));
+      }, this);
+      return res;
+    } else if (kind == "file" || kind == "blob" || kind == "date") {
+      return aObject;
+    } else if (kind == "primitive") {
+      return this.convertDataURIToBlob(aObject);
+    }
+
+    // Fall-through, we now have a dictionary object.
+    for (let prop in aObject) {
+      aObject[prop] = this.prepareValue(aObject[prop]);
+    }
+    return aObject;
+  },
+
+  init: function init() {
+    this.initDBHelper(SETTINGSDB_NAME, SETTINGSDB_VERSION,
+                      [SETTINGSSTORE_NAME]);
+  }
+}