A collapsed (caret) selection should be collapsed in the accessibility tree

(i.e. focusObject == anchorObject)

Test: verify that moving a caret (*not a selection*) never results in a non-collapsed selection in the accessibility tree data
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I29f3d807fd7d9e29b997e3f1969f60d7a99b170a
Reviewed-on: https://chromium-review.googlesource.com/884991Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532281}

chrome/browser/resources/chromeos/chromevox/cvox2/background/editing.js

@@ -816,7 +816,7 @@ editing.EditableLine.prototype = {
     var finder = this.lineStart_;
     while (finder.previousSibling) {
       finder = finder.previousSibling;
-      textCountBeforeLineStart += finder.name.length;
+      textCountBeforeLineStart += finder.name ? finder.name.length : 0;
     }
     this.localLineStartContainerOffset_ = textCountBeforeLineStart;
 
@@ -828,7 +828,7 @@ editing.EditableLine.prototype = {
     finder = this.lineEnd_;
     while (finder.nextSibling) {
       finder = finder.nextSibling;
-      textCountAfterLineEnd += finder.name.length;
+      textCountAfterLineEnd += finder.name ? finder.name.length : 0;
     }
 
     if (this.lineEndContainer_.name) {

third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp

@@ -1794,14 +1794,10 @@ AXObject::AXRange AXLayoutObject::Selection() const {
   VisiblePosition visible_start = selection.VisibleStart();
   Position start = visible_start.ToParentAnchoredPosition();
   TextAffinity start_affinity = visible_start.Affinity();
-  VisiblePosition visible_end = selection.VisibleEnd();
-  Position end = visible_end.ToParentAnchoredPosition();
-  TextAffinity end_affinity = visible_end.Affinity();
-
   Node* anchor_node = start.AnchorNode();
   DCHECK(anchor_node);
-
   AXLayoutObject* anchor_object = nullptr;
+
   // Find the closest node that has a corresponding AXObject.
   // This is because some nodes may be aria hidden or might not even have
   // a layout object if they are part of the shadow DOM.
@@ -1815,10 +1811,20 @@ AXObject::AXRange AXLayoutObject::Selection() const {
     else
       anchor_node = anchor_node->parentNode();
   }
+  if (!anchor_object)
+    return AXRange();
+  int anchor_offset = anchor_object->IndexForVisiblePosition(visible_start);
+  DCHECK_GE(anchor_offset, 0);
+  if (selection.IsCaret()) {
+    return AXRange(anchor_object, anchor_offset, start_affinity, anchor_object,
+                   anchor_offset, start_affinity);
+  }
 
+  VisiblePosition visible_end = selection.VisibleEnd();
+  Position end = visible_end.ToParentAnchoredPosition();
+  TextAffinity end_affinity = visible_end.Affinity();
   Node* focus_node = end.AnchorNode();
   DCHECK(focus_node);
-
   AXLayoutObject* focus_object = nullptr;
   while (focus_node) {
     focus_object = GetUnignoredObjectFromNode(*focus_node);
@@ -1830,12 +1836,8 @@ AXObject::AXRange AXLayoutObject::Selection() const {
     else
       focus_node = focus_node->parentNode();
   }
-
-  if (!anchor_object || !focus_object)
+  if (!focus_object)
     return AXRange();
-
-  int anchor_offset = anchor_object->IndexForVisiblePosition(visible_start);
-  DCHECK_GE(anchor_offset, 0);
   int focus_offset = focus_object->IndexForVisiblePosition(visible_end);
   DCHECK_GE(focus_offset, 0);
   return AXRange(anchor_object, anchor_offset, start_affinity, focus_object,