Refactor TTS logic in Select to Speak

Refactored the underlying logic of STS. Previously, STS combines node enqueue, navigation control, and TTS playing in one function (i.e., startSpeechQueue_). I separate these functionalities by adding five navigation state variables. Then, enqueue nodes in startSpeechQueue_, play TTS via startCurrentNodeGroup_, and control navigation by manipulating the navigation state variables.

With this CL, STS will enqueue content to TTS one nodeGroup at a time. Previously, STS enqueued all selected nodeGroups to TTS. To reflect this change, I modify the tests.

More details notes:
1. Refactor function updateNodeHighlight_ as we don't need the opt_endIndex in this function.
2. Create function syncCurrentNodeWithCharIndex_, which reuses code logic from the previous function onTtsWordEvent_.
3. Split function startSpeechQueue_ into (1) startSpeechQueue_, (2) startCurrentNodeGroup_, and (3) startNodeGroupAfter_. Function startSpeechQueue_ adds new content to the speaking queue and starts TTS using startCurrentNodeGroup_, which starts reading the current NodeGroup based on the five navigation state variables. Function startNodeGroupAfter_ allows us the change the navigation state variables to the next NodeGroup.

AX-Relnotes: N/A

Bug: 1143817
Change-Id: I1aa719786108e0f98fda36ebade7536967cfd2ce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2565698Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Akihiro Ota <akihiroota@chromium.org>
Commit-Queue: Lei Shi <leileilei@google.com>
Cr-Commit-Position: refs/heads/master@{#833620}

chrome/browser/resources/chromeos/accessibility/select_to_speak/mock_tts.js

@@ -53,6 +53,13 @@ MockTts.prototype = {
       this.speechCallbackStack_.pop()(utterance);
     }
   },
+  finishPendingUtterance() {
+    this.pendingUtterances_ = [];
+    this.currentlySpeaking_ = false;
+    if (this.options_) {
+      this.options_.onEvent({type: 'end'});
+    }
+  },
   stop() {
     this.pendingUtterances_ = [];
     this.currentlySpeaking_ = false;

chrome/browser/resources/chromeos/accessibility/select_to_speak/select_to_speak_keystroke_selection_test.js

@@ -179,9 +179,11 @@ TEST_F(
                   assertTrue(this.mockTts.currentlySpeaking());
                   this.assertEqualsCollapseWhitespace(
                       this.mockTts.pendingUtterances()[0], 'Selected text');
-                  if (this.mockTts.pendingUtterances().length === 2) {
+
+                  this.mockTts.finishPendingUtterance();
+                  if (this.mockTts.pendingUtterances().length === 1) {
                     this.assertEqualsCollapseWhitespace(
-                        this.mockTts.pendingUtterances()[1], '');
+                        this.mockTts.pendingUtterances()[0], '');
                   }
                 }),
                 false);
@@ -321,11 +323,14 @@ TEST_F(
           function() {
             this.triggerReadSelectedText();
             assertTrue(this.mockTts.currentlySpeaking());
-            assertEquals(this.mockTts.pendingUtterances().length, 2);
+            assertEquals(this.mockTts.pendingUtterances().length, 1);
             this.assertEqualsCollapseWhitespace(
                 this.mockTts.pendingUtterances()[0], 'paragraph');
+
+            this.mockTts.finishPendingUtterance();
+            assertEquals(this.mockTts.pendingUtterances().length, 1);
             this.assertEqualsCollapseWhitespace(
-                this.mockTts.pendingUtterances()[1], 'text field');
+                this.mockTts.pendingUtterances()[0], 'text field');
           });
     });
 
@@ -343,11 +348,14 @@ TEST_F(
           function() {
             this.triggerReadSelectedText();
             assertTrue(this.mockTts.currentlySpeaking());
-            assertEquals(this.mockTts.pendingUtterances().length, 2);
+            assertEquals(this.mockTts.pendingUtterances().length, 1);
             this.assertEqualsCollapseWhitespace(
                 this.mockTts.pendingUtterances()[0], 'one');
+
+            this.mockTts.finishPendingUtterance();
+            assertEquals(this.mockTts.pendingUtterances().length, 1);
             this.assertEqualsCollapseWhitespace(
-                this.mockTts.pendingUtterances()[1], 'two three');
+                this.mockTts.pendingUtterances()[0], 'two three');
           });
     });
 
@@ -470,9 +478,11 @@ TEST_F(
             assertTrue(this.mockTts.pendingUtterances().length > 0);
             this.assertEqualsCollapseWhitespace(
                 this.mockTts.pendingUtterances()[0], 'Some text');
-            if (this.mockTts.pendingUtterances().length > 1) {
+
+            this.mockTts.finishPendingUtterance();
+            if (this.mockTts.pendingUtterances().length > 0) {
               this.assertEqualsCollapseWhitespace(
-                  this.mockTts.pendingUtterances()[1], '');
+                  this.mockTts.pendingUtterances()[0], '');
             }
           });
     });
@@ -542,11 +552,14 @@ TEST_F(
       this.runWithLoadedTree(html, function() {
         this.triggerReadSelectedText();
         assertTrue(this.mockTts.currentlySpeaking());
-        assertEquals(this.mockTts.pendingUtterances().length, 2);
+        assertEquals(this.mockTts.pendingUtterances().length, 1);
         this.assertEqualsCollapseWhitespace(
             this.mockTts.pendingUtterances()[0], 'b c');
+
+        this.mockTts.finishPendingUtterance();
+        assertEquals(this.mockTts.pendingUtterances().length, 1);
         this.assertEqualsCollapseWhitespace(
-            this.mockTts.pendingUtterances()[1], 'd e');
+            this.mockTts.pendingUtterances()[0], 'd e');
       });
     });
 
@@ -567,8 +580,10 @@ TEST_F(
             assertTrue(this.mockTts.currentlySpeaking());
             this.assertEqualsCollapseWhitespace(
                 this.mockTts.pendingUtterances()[0], 'a b c');
+
+            this.mockTts.finishPendingUtterance();
             this.assertEqualsCollapseWhitespace(
-                this.mockTts.pendingUtterances()[1], 'd e f');
+                this.mockTts.pendingUtterances()[0], 'd e f');
           });
     });
 
@@ -619,12 +634,18 @@ TEST_F(
             assertTrue(this.mockTts.currentlySpeaking());
             this.assertEqualsCollapseWhitespace(
                 this.mockTts.pendingUtterances()[0], 'Column 1, Text 1');
+
+            this.mockTts.finishPendingUtterance();
             this.assertEqualsCollapseWhitespace(
-                this.mockTts.pendingUtterances()[1], 'Column 1, Text 2');
+                this.mockTts.pendingUtterances()[0], 'Column 1, Text 2');
+
+            this.mockTts.finishPendingUtterance();
             this.assertEqualsCollapseWhitespace(
-                this.mockTts.pendingUtterances()[2], 'Column 2, Text 1');
+                this.mockTts.pendingUtterances()[0], 'Column 2, Text 1');
+
+            this.mockTts.finishPendingUtterance();
             this.assertEqualsCollapseWhitespace(
-                this.mockTts.pendingUtterances()[3], 'Column 2, Text 2');
+                this.mockTts.pendingUtterances()[0], 'Column 2, Text 2');
           });
     });
 TEST_F(

chrome/browser/resources/chromeos/accessibility/select_to_speak/select_to_speak_mouse_selection_test.js

@@ -83,6 +83,7 @@ TEST_F(
                 assertEquals(this.mockTts.pendingUtterances().length, 1);
                 this.assertEqualsCollapseWhitespace(
                     utterance, 'This is some text');
+                this.mockTts.finishPendingUtterance();
               }),
               this.newCallback(function(utterance) {
                 this.assertEqualsCollapseWhitespace(