[Switch Access] Refactor Commands, Preferences, and EventHelper classes

Refactors three Switch Access classes for clarity, consistency, and
readability.

Bug: None
Change-Id: Ib81a279cef24348f997f870f208413245a8c2357
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2064790Reviewed-by: Akihiro Ota <akihiroota@chromium.org>
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Cr-Commit-Position: refs/heads/master@{#744045}

chrome/browser/resources/chromeos/accessibility/switch_access/commands.js

@@ -8,14 +8,6 @@ const SwitchAccessCommand = chrome.accessibilityPrivate.SwitchAccessCommand;
  * Runs user commands.
  */
 class Commands {
-  // ============= Static Methods ===============
-
-  static initialize() {
-    Commands.instance = new Commands();
-  }
-
-  // ============= Private Methods ===============
-
   /** @private */
   constructor() {
     /**
@@ -32,6 +24,10 @@ class Commands {
         this.runCommand_.bind(this));
   }
 
+  static initialize() {
+    Commands.instance = new Commands();
+  }
+
   /**
    * Run the function binding for the specified command.
    * @param {!SwitchAccessCommand} command

chrome/browser/resources/chromeos/accessibility/switch_access/event_helper.js

@@ -25,7 +25,7 @@ const EventHelper = {
    * Sends a synthetic mouse event.
    * @param {number} x
    * @param {number} y
-   * @param {number=} delayMs The delay between mouse press and mouse release,
+   * @param {?number} delayMs The delay between mouse press and mouse release,
    *     in milliseconds.
    */
   simulateMouseClick: (x, y, delayMs) => {
@@ -37,7 +37,7 @@ const EventHelper = {
       chrome.accessibilityPrivate.sendSyntheticMouseEvent({type, x, y});
     };
 
-    if (delayMs) {
+    if (delayMs !== null) {
       setTimeout(callback, delayMs);
     } else {
       callback();

chrome/browser/resources/chromeos/accessibility/switch_access/preferences.js

@@ -6,14 +6,6 @@
  * Class to manage user preferences.
  */
 class SwitchAccessPreferences {
-  // =============== Static Methods ==============
-
-  static initialize() {
-    SwitchAccessPreferences.instance = new SwitchAccessPreferences();
-  }
-
-  // =============== Private Methods ==============
-
   /** @private */
   constructor() {
     /**
@@ -26,6 +18,14 @@ class SwitchAccessPreferences {
     this.init_();
   }
 
+  // =============== Static Methods ==============
+
+  static initialize() {
+    SwitchAccessPreferences.instance = new SwitchAccessPreferences();
+  }
+
+  // =============== Private Methods ==============
+
   /**
    * Get the boolean value for the given name, or |null| if the value is not a
    * boolean or does not exist.
@@ -67,6 +67,32 @@ class SwitchAccessPreferences {
         (prefs) => this.updateFromSettings_(prefs, true /* isFirstLoad */));
   }
 
+  /**
+   * Whether the current settings configuration is reasonably usable;
+   * specifically, whether there is a way to select and a way to navigate.
+   * @return {boolean}
+   * @private
+   */
+  settingsAreConfigured_() {
+    const selectSetting =
+        this.getNumber_(SAConstants.Preference.SELECT_SETTING);
+    const nextSetting = this.getNumber_(SAConstants.Preference.NEXT_SETTING);
+    const previousSetting =
+        this.getNumber_(SAConstants.Preference.PREVIOUS_SETTING);
+    const autoScanEnabled =
+        !!this.getBoolean_(SAConstants.Preference.AUTO_SCAN_ENABLED);
+
+    if (!selectSetting) {
+      return false;
+    }
+
+    if (nextSetting || previousSetting) {
+      return true;
+    }
+
+    return autoScanEnabled;
+  }
+
   /**
    * Updates the cached preferences.
    * @param {!Array<chrome.settingsPrivate.PrefObject>} preferences
@@ -76,7 +102,7 @@ class SwitchAccessPreferences {
   updateFromSettings_(preferences, isFirstLoad = false) {
     for (const pref of preferences) {
       // Ignore preferences that are not used by Switch Access.
-      if (!Object.values(SAConstants.Preference).includes(pref.key)) {
+      if (!this.usesPreference_(pref)) {
         continue;
       }
 
@@ -106,45 +132,17 @@ class SwitchAccessPreferences {
       }
     }
 
-    if (isFirstLoad) {
-      this.onInitialLoadComplete_();
-    }
-  }
-
-  /**
-   * Called when the preferences are finished loading for the first time.
-   * @private
-   */
-  onInitialLoadComplete_() {
-    if (!this.settingsAreConfigured_()) {
+    if (isFirstLoad && !this.settingsAreConfigured_()) {
       chrome.accessibilityPrivate.openSettingsSubpage(
           'manageAccessibility/switchAccess');
     }
   }
 
   /**
-   * Whether the current settings configuration is reasonably usable;
-   * specifically, whether there is a way to select and a way to navigate.
+   * @param {!chrome.settingsPrivate.PrefObject} pref
    * @return {boolean}
-   * @private
    */
-  settingsAreConfigured_() {
-    const selectSetting =
-        this.getNumber_(SAConstants.Preference.SELECT_SETTING);
-    const nextSetting = this.getNumber_(SAConstants.Preference.NEXT_SETTING);
-    const previousSetting =
-        this.getNumber_(SAConstants.Preference.PREVIOUS_SETTING);
-    const autoScanEnabled =
-        !!this.getBoolean_(SAConstants.Preference.AUTO_SCAN_ENABLED);
-
-    if (!selectSetting) {
-      return false;
-    }
-
-    if (nextSetting || previousSetting) {
-      return true;
-    }
-
-    return autoScanEnabled;
+  usesPreference_(pref) {
+    return Object.values(SAConstants.Preference).includes(pref.key);
   }
 }