Fix resuming from selection that ended in space in Select-to-Speak

Previously, at the end of a nodeGroup, we use the trimmed text of the
nodeGroup to update currentCharIndex_. This approach causes issues when
the user resumes from selection that ended in space.

Bug: 1167435
Change-Id: Ifa74c459100f6fd444f6200b09eec1fe2f2b4042
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2638917Reviewed-by: Katie Dektar <katie@chromium.org>
Commit-Queue: Lei Shi <leileilei@google.com>
Cr-Commit-Position: refs/heads/master@{#845339}

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

@@ -1602,10 +1602,15 @@ export class SelectToSpeak {
   onNodeGroupSpeakingCompleted_() {
     const currentNodeGroup = this.getCurrentNodeGroup_();
 
-    // Update the current char index to the end of the text content in this
-    // nodeGroup.
+    // Update the current char index to the end of the node group. If the
+    // endOffset is undefined, we set the index to the length of the node
+    // group's text.
+    if (currentNodeGroup && currentNodeGroup.endOffset !== undefined) {
+      this.currentCharIndex_ = currentNodeGroup.endOffset;
+    } else {
       const nodeGroupText = (currentNodeGroup && currentNodeGroup.text) || '';
-    this.currentCharIndex_ = nodeGroupText.trimEnd().length;
+      this.currentCharIndex_ = nodeGroupText.length;
+    }
 
     const isLastNodeGroup =
         (this.currentNodeGroupIndex_ === this.currentNodeGroups_.length - 1);

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

@@ -854,6 +854,48 @@ TEST_F(
           });
     });
 
+TEST_F(
+    'SelectToSpeakNavigationControlTest', 'ResumeFromSelectionEndingInSpace',
+    function() {
+      const bodyHtml = '<p>This is some text with space.</p>';
+      const setFocusCallback = this.newCallback((root) => {
+        const node = this.findTextNode(root, 'This is some text with space.');
+        // Sets the selection to "This ".
+        chrome.automation.setDocumentSelection({
+          anchorObject: node,
+          anchorOffset: 0,
+          focusObject: node,
+          focusOffset: 5
+        });
+      });
+      this.runWithLoadedTree(bodyHtml, (root) => {
+        root.addEventListener(
+            'documentSelectionChanged', this.newCallback((event) => {
+              this.triggerReadSelectedText();
+
+              assertTrue(this.mockTts.currentlySpeaking());
+              assertEquals(this.mockTts.pendingUtterances().length, 1);
+              this.assertEqualsCollapseWhitespace(
+                  this.mockTts.pendingUtterances()[0], 'This');
+
+              // Finishes the current utterance.
+              this.mockTts.finishPendingUtterance();
+
+              // Hitting resume will start from the remaining content of the
+              // paragraph.
+              selectToSpeak.onSelectToSpeakPanelAction_(
+                  chrome.accessibilityPrivate.SelectToSpeakPanelAction.RESUME);
+              assertTrue(this.mockTts.currentlySpeaking());
+              assertEquals(this.mockTts.pendingUtterances().length, 1);
+              this.assertEqualsCollapseWhitespace(
+                  this.mockTts.pendingUtterances()[0],
+                  'is some text with space.');
+            }),
+            false);
+        setFocusCallback(root);
+      });
+    });
+
 TEST_F('SelectToSpeakNavigationControlTest', 'ResizeWhilePlaying', function() {
   const longLine =
       'Second paragraph is longer than 300 pixels and will wrap when resized';