Reland "Refactor intent usage in ChromeVox"

This is a reland of 39716b26

Original change's description:
> Refactor intent usage in ChromeVox
>
> This is a purely refactoring change to set up ChromeVox to use all
> possible intents. IntentHandler, the newly introduced class, will
> cleanly process all intents, along with whatever computed metadata is
> needed (e.g. EditableLine).
>
> R=akihiroota@chromium.org, nektar@chromium.org
>
> AX-Relnotes: n/a
> Test: existing browser_tests --gtest_filter=ChromeVoxEditing*.*
> Change-Id: I74d9454794fc6a40075bbf56fb0037b607c2b974
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2594240
> Commit-Queue: David Tseng <dtseng@chromium.org>
> Reviewed-by: Akihiro Ota <akihiroota@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#838241}
TBR=akihiroota@chromium.org, nektar@chromium.org, dtseng@chromium.org

Change-Id: I4fa306dc747cd623cdbb38f11c8ace144730af57
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2601639
Commit-Queue: Lan Wei <lanwei@chromium.org>
Reviewed-by: Lan Wei <lanwei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#839027}

chrome/browser/resources/chromeos/accessibility/chromevox/BUILD.gn

@@ -48,7 +48,9 @@ chromevox_modules = [
   "background/desktop_automation_handler.js",
   "background/download_handler.js",
   "background/earcon_engine.js",
-  "background/editing.js",
+  "background/editing/editable_line.js",
+  "background/editing/editing.js",
+  "background/editing/intent_handler.js",
   "background/event_source.js",
   "background/find_handler.js",
   "background/focus_automation_handler.js",
@@ -450,7 +452,7 @@ if (is_chromeos_ash) {
       "background/color_test.js",
       "background/cursors_test.js",
       "background/download_handler_test.js",
-      "background/editing_test.js",
+      "background/editing/editing_test.js",
       "background/keyboard_handler_test.js",
       "background/live_regions_test.js",
       "background/locale_output_helper_test.js",

chrome/browser/resources/chromeos/accessibility/chromevox/background/editing_test.js → chrome/browser/resources/chromeos/accessibility/chromevox/background/editing/editing_test.js

@@ -267,7 +267,8 @@ TEST_F(
           `
     <div role="textbox" contenteditable>
       <p style="font-size:20px; font-family:times">
-        <b style="color:#ff0000">Move</b> <i>through</i> <u style="font-family:georgia">text</u>
+        <b style="color:#ff0000">Move</b>
+        <i>through</i> <u style="font-family:georgia">text</u>
         by <strike style="font-size:12px; color:#0000ff">character</strike>
         <a href="#">test</a>!
       </p>

chrome/browser/resources/chromeos/accessibility/chromevox/background/editing/intent_handler.js

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview Handles automation intents for speech feedback.
+ */
+
+goog.provide('IntentHandler');
+
+goog.require('editing.EditableLine');
+
+goog.scope(function() {
+const AutomationIntent = chrome.automation.AutomationIntent;
+const IntentCommandType = chrome.automation.IntentCommandType;
+const IntentTextBoundaryType = chrome.automation.IntentTextBoundaryType;
+
+/**
+ * A stateless class that turns intents into speech.
+ */
+IntentHandler = class {
+  /**
+   * Called when intents are received from an AutomationEvent.
+   * @param {!Array<AutomationIntent>} intents
+   * @param {!editing.EditableLine} cur The current line.
+   * @param {editing.EditableLine} prev The previous line.
+   * @return {boolean} Whether intents are handled.
+   */
+  static onIntents(intents, cur, prev) {
+    if (intents.length === 0) {
+      return false;
+    }
+
+    // Currently, discard all other intents once one is handled.
+    for (let i = 0; i < intents.length; i++) {
+      if (IntentHandler.onIntent(intents[i], cur, prev)) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Called when an intent is received.
+   * @param {!AutomationIntent} intent
+   * @param {!editing.EditableLine} cur The current line.
+   * @param {editing.EditableLine} prev The previous line.
+   * @return {boolean} Whether the intent was handled.
+   */
+  static onIntent(intent, cur, prev) {
+    switch (intent.command) {
+      case IntentCommandType.MOVE_SELECTION:
+        return IntentHandler.onMoveSelection(intent, cur, prev);
+
+        // TODO: implement support.
+      case IntentCommandType.CLEAR_SELECTION:
+      case IntentCommandType.DELETE:
+      case IntentCommandType.DICTATE:
+      case IntentCommandType.EXTEND_SELECTION:
+      case IntentCommandType.FORMAT:
+      case IntentCommandType.HISTORY:
+      case IntentCommandType.INSERT:
+      case IntentCommandType.MARKER:
+      case IntentCommandType.SET_SELECTION:
+        break;
+    }
+
+    return false;
+  }
+
+  /**
+   * Called when the text selection moves.
+   * @param {!AutomationIntent} intent A move selection
+   *     intent.
+   * @param {!editing.EditableLine} cur The current line.
+   * @param {editing.EditableLine} prev The previous line.
+   * @return {boolean} Whether the intent was handled.
+   */
+  static onMoveSelection(intent, cur, prev) {
+    switch (intent.textBoundary) {
+      case IntentTextBoundaryType.CHARACTER:
+        // Read character to the right of the cursor. It is assumed to be a new
+        // line if empty.
+        // TODO: detect when this is the end of the document; read "end of text"
+        // if so.
+        ChromeVox.tts.speak(
+            cur.text.substring(cur.startOffset, cur.startOffset + 1) || '\n',
+            QueueMode.CATEGORY_FLUSH);
+        return true;
+
+      case IntentTextBoundaryType.LINE_END:
+      case IntentTextBoundaryType.LINE_START:
+      case IntentTextBoundaryType.LINE_START_OR_END:
+        cur.speakLine(prev);
+        return true;
+
+        // TODO: implement support.
+      case IntentTextBoundaryType.FORMAT:
+      case IntentTextBoundaryType.OBJECT:
+      case IntentTextBoundaryType.PAGE_END:
+      case IntentTextBoundaryType.PAGE_START:
+      case IntentTextBoundaryType.PAGE_START_OR_END:
+      case IntentTextBoundaryType.PARAGRAPH_END:
+      case IntentTextBoundaryType.PARAGRAPH_START:
+      case IntentTextBoundaryType.PARAGRAPH_START_OR_END:
+      case IntentTextBoundaryType.SENTENCE_END:
+      case IntentTextBoundaryType.SENTENCE_START:
+      case IntentTextBoundaryType.SENTENCE_START_OR_END:
+      case IntentTextBoundaryType.WEB_PAGE:
+      case IntentTextBoundaryType.WORD_END:
+      case IntentTextBoundaryType.WORD_START:
+      case IntentTextBoundaryType.WORD_START_OR_END:
+        break;
+    }
+
+    return false;
+  }
+};
+});  // goog.scope