Make select-to-speak ignore nodes with user-select:none.

This CL only affects the behavior of Select-to-Speak when STS is
triggered by selection followed by Search-S (it does not affect STS
triggered from the tray or by mouse selection). Since keyboard selection
does not highlight any nodes marked user-select:none, STS follows the
visual behavior here by ignoring these nodes when spoken out as well.
While this causes the behavior to be inconsistent between mouse- and
keyboard-based invocation, it follows the user's mental model: when a
rectangular selection is made with the mouse, STS speaks out everything
within the rectangle that the user draws, whereas when a selection is
made with the cursor and STS invoked from the keyboard, STS speaks out
whatever was actually selected.

Also added a browser test to verify this behavior.

Bug: 830106
Change-Id: I8552e7bda40f150df2ab4bb0338de706a717f30e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2426973
Commit-Queue: Ajit Narayanan <ajitnarayanan@google.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810768}

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

@@ -52,6 +52,20 @@ class NodeUtils {
     return ParagraphUtils.isWhitespace(ParagraphUtils.getNodeName(node));
   }
 
+  /**
+   * Returns true if the node should be ignored by Select-to-Speak because
+   * it was marked with user-select:none. For Inline Text elements, the
+   * parent is marked with this attribute, hence the check.
+   *
+   * @param {!AutomationNode} node The node to test
+   * @return {boolean} whether this node was marked user-select:none
+   */
+  static isNotSelectable(node) {
+    return node &&
+        (node.notUserSelectableStyle ||
+         (node.parent && node.parent.notUserSelectableStyle));
+  }
+
   /**
    * Returns true if a node is invisible for any reason.
    * @param {!AutomationNode} node The node to test

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

@@ -271,7 +271,8 @@ class SelectToSpeak {
     let selectedNode = firstPosition.node;
     if (selectedNode.name && firstPosition.offset < selectedNode.name.length &&
         !NodeUtils.shouldIgnoreNode(
-            selectedNode, /* include offscreen */ true)) {
+            selectedNode, /* include offscreen */ true) &&
+        !NodeUtils.isNotSelectable(selectedNode)) {
       // Initialize to the first node in the list if it's valid and inside
       // of the offset bounds.
       nodes.push(selectedNode);
@@ -304,7 +305,8 @@ class SelectToSpeak {
         }
       }
       if (!NodeUtils.shouldIgnoreNode(
-              selectedNode, /* include offscreen */ true)) {
+              selectedNode, /* include offscreen */ true) &&
+          !NodeUtils.isNotSelectable(selectedNode)) {
         nodes.push(selectedNode);
       }
     }

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

@@ -226,6 +226,25 @@ TEST_F(
           'This is some bold text');
     });
 
+TEST_F(
+    'SelectToSpeakKeystrokeSelectionTest', 'IgnoresTextMarkedNotUserSelectable',
+    function() {
+      this.testReadTextAtKeystroke(
+          '<div><p>This is some <span style="user-select:none">unselectable</span> text</p></div>',
+          function(desktop) {
+            const firstNode =
+                this.findTextNode(desktop, 'This is some ').root.children[0];
+            const lastNode = this.findTextNode(desktop, ' text');
+            chrome.automation.setDocumentSelection({
+              anchorObject: firstNode,
+              anchorOffset: 0,
+              focusObject: lastNode,
+              focusOffset: 5
+            });
+          },
+          'This is some text');
+    });
+
 TEST_F(
     'SelectToSpeakKeystrokeSelectionTest',
     'HandlesSingleImageCorrectlyWithAutomation', function() {

extensions/common/api/automation.idl

@@ -1058,6 +1058,9 @@ enum GeneratedEventType {
     // The affinity of the tree selection end, if any.
     DOMString? selectionEndAffinity;
 
+    // Indicates that the node is marked user-select:none
+    boolean? notUserSelectableStyle;
+
     //
     // Range attributes.
     //

extensions/renderer/resources/automation/automation_node.js

@@ -1317,8 +1317,8 @@ var stringAttributes = [
 
 var boolAttributes = [
   'busy', 'clickable', 'containerLiveAtomic', 'containerLiveBusy',
-  'editableRoot', 'liveAtomic', 'modal', 'scrollable', 'selected',
-  'supportsTextLocation'
+  'editableRoot', 'liveAtomic', 'modal', 'notUserSelectableStyle', 'scrollable',
+  'selected', 'supportsTextLocation'
 ];
 
 var intAttributes = [