Use nextOnline for the line break predicate

R=akihiroota@chromium.org

AX-Relnotes: ChromeVox will combine inline elements such as <strong>, <b> when navigating by line (Search+up/down).
Fixed: 1116646
Change-Id: Ide1afd67dc4492847968f42b81e4d7251f4cc95c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2372927
Commit-Queue: David Tseng <dtseng@chromium.org>
Reviewed-by: Akihiro Ota <akihiroota@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801204}

chrome/browser/resources/chromeos/accessibility/chromevox/background/background_test.js

@@ -2892,3 +2892,17 @@ TEST_F('ChromeVoxBackgroundTest', 'SortDirection', function() {
             .replay();
       });
 });
+
+TEST_F('ChromeVoxBackgroundTest', 'InlineLineNavigation', function() {
+  const mockFeedback = this.createMockFeedback();
+  this.runWithLoadedTree(
+      `
+    <p>start</p>
+    <p><strong>This</strong><b>is</b>a <em>test</em></p>
+  `,
+      function(root) {
+        mockFeedback.call(doCmd('nextLine'))
+            .expectSpeech('This', 'is', 'a ', 'test')
+            .replay();
+      });
+});

chrome/browser/resources/chromeos/accessibility/common/automation_predicate.js

@@ -293,7 +293,10 @@ AutomationPredicate = class {
    * @return {boolean}
    */
   static linebreak(first, second) {
-    // TODO(dtseng): Use next/previousOnLine once available.
+    if (first.nextOnLine == second) {
+      return false;
+    }
+
     const fl = first.unclippedLocation;
     const sl = second.unclippedLocation;
     return fl.top != sl.top || (fl.top + fl.height != sl.top + sl.height);