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diff --git a/toolkit/components/search/SearchSuggestionController.jsm b/toolkit/components/search/SearchSuggestionController.jsm
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+++ b/toolkit/components/search/SearchSuggestionController.jsm
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+/* 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";
+
+this.EXPORTED_SYMBOLS = ["SearchSuggestionController"];
+
+const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/Promise.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "NS_ASSERT", "resource://gre/modules/debug.js");
+
+const SEARCH_RESPONSE_SUGGESTION_JSON = "application/x-suggestions+json";
+const DEFAULT_FORM_HISTORY_PARAM      = "searchbar-history";
+const HTTP_OK            = 200;
+const REMOTE_TIMEOUT     = 500; // maximum time (ms) to wait before giving up on a remote suggestions
+const BROWSER_SUGGEST_PREF = "browser.search.suggest.enabled";
+
+/**
+ * Remote search suggestions will be shown if gRemoteSuggestionsEnabled
+ * is true. Global because only one pref observer is needed for all instances.
+ */
+var gRemoteSuggestionsEnabled = Services.prefs.getBoolPref(BROWSER_SUGGEST_PREF);
+Services.prefs.addObserver(BROWSER_SUGGEST_PREF, function(aSubject, aTopic, aData) {
+  gRemoteSuggestionsEnabled = Services.prefs.getBoolPref(BROWSER_SUGGEST_PREF);
+}, false);
+
+/**
+ * SearchSuggestionController.jsm exists as a helper module to allow multiple consumers to request and display
+ * search suggestions from a given engine, regardless of the base implementation. Much of this
+ * code was originally in nsSearchSuggestions.js until it was refactored to separate it from the
+ * nsIAutoCompleteSearch dependency.
+ * One instance of SearchSuggestionController should be used per field since form history results are cached.
+ */
+
+/**
+ * @param {function} [callback] - Callback for search suggestion results. You can use the promise
+ *                                returned by the search method instead if you prefer.
+ * @constructor
+ */
+this.SearchSuggestionController = function SearchSuggestionController(callback = null) {
+  this._callback = callback;
+};
+
+this.SearchSuggestionController.prototype = {
+  /**
+   * The maximum number of local form history results to return. This limit is
+   * only enforced if remote results are also returned.
+   */
+  maxLocalResults: 5,
+
+  /**
+   * The maximum number of remote search engine results to return.
+   * We'll actually only display at most
+   * maxRemoteResults - <displayed local results count> remote results.
+   */
+  maxRemoteResults: 10,
+
+  /**
+   * The maximum time (ms) to wait before giving up on a remote suggestions.
+   */
+  remoteTimeout: REMOTE_TIMEOUT,
+
+  /**
+   * The additional parameter used when searching form history.
+   */
+  formHistoryParam: DEFAULT_FORM_HISTORY_PARAM,
+
+  // Private properties
+  /**
+   * The last form history result used to improve the performance of subsequent searches.
+   * This shouldn't be used for any other purpose as it is never cleared and therefore could be stale.
+   */
+  _formHistoryResult: null,
+
+  /**
+   * The remote server timeout timer, if applicable. The timer starts when form history
+   * search is completed.
+   */
+  _remoteResultTimer: null,
+
+  /**
+   * The deferred for the remote results before its promise is resolved.
+   */
+  _deferredRemoteResult: null,
+
+  /**
+   * The optional result callback registered from the constructor.
+   */
+  _callback: null,
+
+  /**
+   * The XMLHttpRequest object for remote results.
+   */
+  _request: null,
+
+  // Public methods
+
+  /**
+   * Fetch search suggestions from all of the providers. Fetches in progress will be stopped and
+   * results from them will not be provided.
+   *
+   * @param {string} searchTerm - the term to provide suggestions for
+   * @param {bool} privateMode - whether the request is being made in the context of private browsing
+   * @param {nsISearchEngine} engine - search engine for the suggestions.
+   * @param {int} userContextId - the userContextId of the selected tab.
+   *
+   * @return {Promise} resolving to an object containing results or null.
+   */
+  fetch: function(searchTerm, privateMode, engine, userContextId) {
+    // There is no smart filtering from previous results here (as there is when looking through
+    // history/form data) because the result set returned by the server is different for every typed
+    // value - e.g. "ocean breathes" does not return a subset of the results returned for "ocean".
+
+    this.stop();
+
+    if (!Services.search.isInitialized) {
+      throw new Error("Search not initialized yet (how did you get here?)");
+    }
+    if (typeof privateMode === "undefined") {
+      throw new Error("The privateMode argument is required to avoid unintentional privacy leaks");
+    }
+    if (!(engine instanceof Ci.nsISearchEngine)) {
+      throw new Error("Invalid search engine");
+    }
+    if (!this.maxLocalResults && !this.maxRemoteResults) {
+      throw new Error("Zero results expected, what are you trying to do?");
+    }
+    if (this.maxLocalResults < 0 || this.maxRemoteResults < 0) {
+      throw new Error("Number of requested results must be positive");
+    }
+
+    // Array of promises to resolve before returning results.
+    let promises = [];
+    this._searchString = searchTerm;
+
+    // Remote results
+    if (searchTerm && gRemoteSuggestionsEnabled && this.maxRemoteResults &&
+        engine.supportsResponseType(SEARCH_RESPONSE_SUGGESTION_JSON)) {
+      this._deferredRemoteResult = this._fetchRemote(searchTerm, engine, privateMode, userContextId);
+      promises.push(this._deferredRemoteResult.promise);
+    }
+
+    // Local results from form history
+    if (this.maxLocalResults) {
+      let deferredHistoryResult = this._fetchFormHistory(searchTerm);
+      promises.push(deferredHistoryResult.promise);
+    }
+
+    function handleRejection(reason) {
+      if (reason == "HTTP request aborted") {
+        // Do nothing since this is normal.
+        return null;
+      }
+      Cu.reportError("SearchSuggestionController rejection: " + reason);
+      return null;
+    }
+    return Promise.all(promises).then(this._dedupeAndReturnResults.bind(this), handleRejection);
+  },
+
+  /**
+   * Stop pending fetches so no results are returned from them.
+   *
+   * Note: If there was no remote results fetched, the fetching cannot be stopped and local results
+   * will still be returned because stopping relies on aborting the XMLHTTPRequest to reject the
+   * promise for Promise.all.
+   */
+  stop: function() {
+    if (this._request) {
+      this._request.abort();
+    } else if (!this.maxRemoteResults) {
+      Cu.reportError("SearchSuggestionController: Cannot stop fetching if remote results were not "+
+                     "requested");
+    }
+    this._reset();
+  },
+
+  // Private methods
+
+  _fetchFormHistory: function(searchTerm) {
+    let deferredFormHistory = Promise.defer();
+
+    let acSearchObserver = {
+      // Implements nsIAutoCompleteSearch
+      onSearchResult: (search, result) => {
+        this._formHistoryResult = result;
+
+        if (this._request) {
+          this._remoteResultTimer = Cc["@mozilla.org/timer;1"].
+                                    createInstance(Ci.nsITimer);
+          this._remoteResultTimer.initWithCallback(this._onRemoteTimeout.bind(this),
+                                                   this.remoteTimeout || REMOTE_TIMEOUT,
+                                                   Ci.nsITimer.TYPE_ONE_SHOT);
+        }
+
+        switch (result.searchResult) {
+          case Ci.nsIAutoCompleteResult.RESULT_SUCCESS:
+          case Ci.nsIAutoCompleteResult.RESULT_NOMATCH:
+            if (result.searchString !== this._searchString) {
+              deferredFormHistory.resolve("Unexpected response, this._searchString does not match form history response");
+              return;
+            }
+            let fhEntries = [];
+            for (let i = 0; i < result.matchCount; ++i) {
+              fhEntries.push(result.getValueAt(i));
+            }
+            deferredFormHistory.resolve({
+              result: fhEntries,
+              formHistoryResult: result,
+            });
+            break;
+          case Ci.nsIAutoCompleteResult.RESULT_FAILURE:
+          case Ci.nsIAutoCompleteResult.RESULT_IGNORED:
+            deferredFormHistory.resolve("Form History returned RESULT_FAILURE or RESULT_IGNORED");
+            break;
+        }
+      },
+    };
+
+    let formHistory = Cc["@mozilla.org/autocomplete/search;1?name=form-history"].
+                      createInstance(Ci.nsIAutoCompleteSearch);
+    formHistory.startSearch(searchTerm, this.formHistoryParam || DEFAULT_FORM_HISTORY_PARAM,
+                            this._formHistoryResult,
+                            acSearchObserver);
+    return deferredFormHistory;
+  },
+
+  /**
+   * Fetch suggestions from the search engine over the network.
+   */
+  _fetchRemote: function(searchTerm, engine, privateMode, userContextId) {
+    let deferredResponse = Promise.defer();
+    this._request = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"].
+                    createInstance(Ci.nsIXMLHttpRequest);
+    let submission = engine.getSubmission(searchTerm,
+                                          SEARCH_RESPONSE_SUGGESTION_JSON);
+    let method = (submission.postData ? "POST" : "GET");
+    this._request.open(method, submission.uri.spec, true);
+
+    this._request.setOriginAttributes({userContextId,
+                                       privateBrowsingId: privateMode ? 1 : 0});
+
+    this._request.mozBackgroundRequest = true; // suppress dialogs and fail silently
+
+    this._request.addEventListener("load", this._onRemoteLoaded.bind(this, deferredResponse));
+    this._request.addEventListener("error", (evt) => deferredResponse.resolve("HTTP error"));
+    // Reject for an abort assuming it's always from .stop() in which case we shouldn't return local
+    // or remote results for existing searches.
+    this._request.addEventListener("abort", (evt) => deferredResponse.reject("HTTP request aborted"));
+
+    this._request.send(submission.postData);
+
+    return deferredResponse;
+  },
+
+  /**
+   * Called when the request completed successfully (thought the HTTP status could be anything)
+   * so we can handle the response data.
+   * @private
+   */
+  _onRemoteLoaded: function(deferredResponse) {
+    if (!this._request) {
+      deferredResponse.resolve("Got HTTP response after the request was cancelled");
+      return;
+    }
+
+    let status, serverResults;
+    try {
+      status = this._request.status;
+    } catch (e) {
+      // The XMLHttpRequest can throw NS_ERROR_NOT_AVAILABLE.
+      deferredResponse.resolve("Unknown HTTP status: " + e);
+      return;
+    }
+
+    if (status != HTTP_OK || this._request.responseText == "") {
+      deferredResponse.resolve("Non-200 status or empty HTTP response: " + status);
+      return;
+    }
+
+    try {
+      serverResults = JSON.parse(this._request.responseText);
+    } catch (ex) {
+      deferredResponse.resolve("Failed to parse suggestion JSON: " + ex);
+      return;
+    }
+
+    if (!serverResults[0] ||
+        this._searchString.localeCompare(serverResults[0], undefined,
+                                         { sensitivity: "base" })) {
+      // something is wrong here so drop remote results
+      deferredResponse.resolve("Unexpected response, this._searchString does not match remote response");
+      return;
+    }
+    let results = serverResults[1] || [];
+    deferredResponse.resolve({ result: results });
+  },
+
+  /**
+   * Called when this._remoteResultTimer fires indicating the remote request took too long.
+   */
+  _onRemoteTimeout: function () {
+    this._request = null;
+
+    // FIXME: bug 387341
+    // Need to break the cycle between us and the timer.
+    this._remoteResultTimer = null;
+
+    // The XMLHTTPRequest for suggest results is taking too long
+    // so send out the form history results and cancel the request.
+    if (this._deferredRemoteResult) {
+      this._deferredRemoteResult.resolve("HTTP Timeout");
+      this._deferredRemoteResult = null;
+    }
+  },
+
+  /**
+   * @param {Array} suggestResults - an array of result objects from different sources (local or remote)
+   * @return {Object}
+   */
+  _dedupeAndReturnResults: function(suggestResults) {
+    if (this._searchString === null) {
+      // _searchString can be null if stop() was called and remote suggestions
+      // were disabled (stopping if we are fetching remote suggestions will
+      // cause a promise rejection before we reach _dedupeAndReturnResults).
+      return null;
+    }
+
+    let results = {
+      term: this._searchString,
+      remote: [],
+      local: [],
+      formHistoryResult: null,
+    };
+
+    for (let result of suggestResults) {
+      if (typeof result === "string") { // Failure message
+        Cu.reportError("SearchSuggestionController: " + result);
+      } else if (result.formHistoryResult) { // Local results have a formHistoryResult property.
+        results.formHistoryResult = result.formHistoryResult;
+        results.local = result.result || [];
+      } else { // Remote result
+        results.remote = result.result || [];
+      }
+    }
+
+    // If we have remote results, cap the number of local results
+    if (results.remote.length) {
+      results.local = results.local.slice(0, this.maxLocalResults);
+    }
+
+    // We don't want things to appear in both history and suggestions so remove entries from
+    // remote results that are already in local.
+    if (results.remote.length && results.local.length) {
+      for (let i = 0; i < results.local.length; ++i) {
+        let term = results.local[i];
+        let dupIndex = results.remote.indexOf(term);
+        if (dupIndex != -1) {
+          results.remote.splice(dupIndex, 1);
+        }
+      }
+    }
+
+    // Trim the number of results to the maximum requested (now that we've pruned dupes).
+    results.remote =
+      results.remote.slice(0, this.maxRemoteResults - results.local.length);
+
+    if (this._callback) {
+      this._callback(results);
+    }
+    this._reset();
+
+    return results;
+  },
+
+  _reset: function() {
+    this._request = null;
+    if (this._remoteResultTimer) {
+      this._remoteResultTimer.cancel();
+      this._remoteResultTimer = null;
+    }
+    this._deferredRemoteResult = null;
+    this._searchString = null;
+  },
+};
+
+/**
+ * Determines whether the given engine offers search suggestions.
+ *
+ * @param {nsISearchEngine} engine - The search engine
+ * @return {boolean} True if the engine offers suggestions and false otherwise.
+ */
+this.SearchSuggestionController.engineOffersSuggestions = function(engine) {
+ return engine.supportsResponseType(SEARCH_RESPONSE_SUGGESTION_JSON);
+};