Avoid endless loop when computing line boundaries in contentEditable.

BUG=535323,572777 Review URL: https://codereview.chromium.org/1548403002 Cr-Commit-Position: refs/heads/master@{#367213}

Avoid endless loop when computing line boundaries in contentEditable.
BUG=535323,572777 Review URL: https://codereview.chromium.org/1548403002 Cr-Commit-Position: refs/heads/master@{#367213}
251167c9 · dmazzoni · Commit bot · 4477e4b7 · 251167c9 · 251167c9
Commit 251167c9 authored Dec 30, 2015 by dmazzoni Committed by Commit bot Dec 31, 2015
2 changed files
--- a/third_party/WebKit/LayoutTests/accessibility/line-for-index-endless-loop.html
+++ b/third_party/WebKit/LayoutTests/accessibility/line-for-index-endless-loop.html
+<!DOCTYPE HTML>
+<script src="../resources/testharness.js"></script>
+<script src="../resources/testharnessreport.js"></script>
+<style>
+.hideAllContainers .container {
+    display: none;
+}
+</style>
+<div class="container" id="contentEditable" contentEditable>
+  <span style="display: inline-block;">
+    <span style="position: absolute;">
+      <span>x</span>
+    </span>
+    <span>2</span>
+    <span style="display: inline-block;"></span>
+  </span>
+  <span>+</span>
+</div>
+<script>
+test(function(t) {
+    var axContentEditable = accessibilityController.accessibleElementById("contentEditable");
+    assert_equals(axContentEditable.lineForIndex(0), 0);
+}, "No endless loop when getting line for index in contentEditable");
+</script>
+<script>
+if (window.testRunner)
+    document.body.className = "hideAllContainers";
+</script>
--- a/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp
@@ -2165,6 +2165,10 @@ void AXLayoutObject::lineBreaks(Vector<int>& lineBreaks) const
        lineBreaks.append(indexForVisiblePosition(visiblePos));
        prevVisiblePos = visiblePos;
        visiblePos = nextLinePosition(visiblePos, 0, HasEditableAXRole);
+        // Make sure we always make forward progress.
+        if (visiblePos.deepEquivalent().compareTo(prevVisiblePos.deepEquivalent()) < 0)
+            break;
    }
 }