add support for autocomplete delay

src/UserSettingsStore.js

@@ -139,7 +139,7 @@ module.exports = {
 
     getSyncedSetting: function(type, defaultValue = null) {
         var settings = this.getSyncedSettings();
-        return settings.hasOwnProperty(type) ? settings[type] : null;
+        return settings.hasOwnProperty(type) ? settings[type] : defaultValue;
     },
 
     setSyncedSetting: function(type, value) {
@@ -156,7 +156,7 @@ module.exports = {
 
     getLocalSetting: function(type, defaultValue = null) {
         var settings = this.getLocalSettings();
-        return settings.hasOwnProperty(type) ? settings[type] : null;
+        return settings.hasOwnProperty(type) ? settings[type] : defaultValue;
     },
 
     setLocalSetting: function(type, value) {

src/autocomplete/Autocompleter.js

@@ -43,7 +43,7 @@ export async function getCompletions(query: string, selection: SelectionRange, f
         PROVIDERS.map(provider => {
             return Q(provider.getCompletions(query, selection, force))
                 .timeout(PROVIDER_COMPLETION_TIMEOUT);
-        })
+        }),
     );
 
     return completionsList

src/components/structures/UserSettings.js

@@ -508,6 +508,15 @@ module.exports = React.createClass({
                     { this._renderUrlPreviewSelector() }
                     { SETTINGS_LABELS.map( this._renderSyncedSetting ) }
                     { THEMES.map( this._renderThemeSelector ) }
+                    <table>
+                        <tbody>
+                        <tr>
+                            <td><strong>Autocomplete Delay (ms): </strong></td>
+                            <td><input type="number" defaultValue={UserSettingsStore.getLocalSetting('autocompleteDelay', 200)}
+                                       onChange={(e) => UserSettingsStore.setLocalSetting('autocompleteDelay', +e.target.value)} /> </td>
+                        </tr>
+                        </tbody>
+                    </table>
                 </div>
             </div>
         );

src/components/views/rooms/Autocomplete.js

@@ -6,6 +6,7 @@ import isEqual from 'lodash/isEqual';
 import sdk from '../../../index';
 import type {Completion, SelectionRange} from '../../../autocomplete/Autocompleter';
 import Q from 'q';
+import UserSettingsStore from '../../../UserSettingsStore';
 
 import {getCompletions} from '../../../autocomplete/Autocompleter';
 
@@ -77,9 +78,6 @@ export default class Autocomplete extends React.Component {
             }
         }
 
-        // If no completions were returned, we should turn off force completion.
-        forceComplete = false;
-
         let hide = this.state.hide;
         // These are lists of booleans that indicate whether whether the corresponding provider had a matching pattern
         const oldMatches = this.state.completions.map((completion) => !!completion.command.command),
@@ -90,6 +88,17 @@ export default class Autocomplete extends React.Component {
             hide = false;
         }
 
+        const autocompleteDelay = UserSettingsStore.getSyncedSetting('autocompleteDelay', 200);
+
+        // We had no completions before, but do now, so we should apply our display delay here
+        if (this.state.completionList.length === 0 && completionList.length > 0 &&
+            !forceComplete && autocompleteDelay > 0) {
+            await Q.delay(autocompleteDelay);
+        }
+
+        // Force complete is turned off each time since we can't edit the query in that case
+        forceComplete = false;
+
         this.setState({
             completions,
             completionList,