Fix wrapped braille cursor state

Test: navigate within editable text. Hit the 'end' key. Verify the cursor lands on the extra cell padding after this change. Before this change, the cursor "disappears".
Change-Id: I370bb2ae2bc458e4d94a1cd364c381fec3e976da
Reviewed-on: https://chromium-review.googlesource.com/1231982Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592246}

chrome/browser/resources/chromeos/chromevox/braille/pan_strategy.js

@@ -302,6 +302,11 @@ cvox.PanStrategy.prototype = {
       }
     }
 
+    // It's possible the end of the wrapped cursor falls at the
+    // |translatedContent.byteLength| exactly.
+    this.maybeSetWrappedCursor_(
+        index - cellsPadded, wrappedBrailleArray.length);
+
     // Convert the wrapped Braille Uint8 Array back to ArrayBuffer.
     var wrappedBrailleUint8Array = new Uint8Array(wrappedBrailleArray);
     this.wrappedBuffer_ = new ArrayBuffer(wrappedBrailleUint8Array.length);
@@ -327,7 +332,10 @@ cvox.PanStrategy.prototype = {
   },
 
   /**
-   *
+   * Refreshes the wrapped cursor given a mapping from an unwrapped index to a
+   * wrapped index.
+   * @param {number} unwrappedIndex
+   * @param {number} wrappedIndex
    */
   maybeSetWrappedCursor_: function(unwrappedIndex, wrappedIndex) {
     // We only care about the bounds of the index start/end.

chrome/browser/resources/chromeos/chromevox/braille/pan_strategy_test.unitjs

@@ -268,3 +268,27 @@ TEST_F('CvoxPanStrategyUnitTest', 'getCurrentTextViewportContents', function() {
   panner.next();
   assertEquals('789', panner.getCurrentTextViewportContents());
 });
+
+TEST_F('CvoxPanStrategyUnitTest', 'WrappedUnwrappedCursors', function() {
+  var panner = new cvox.PanStrategy();
+  panner.setPanStrategy(true);
+
+  // 30 cells with blank cells at positions 8, 22 and 26.
+  var content = createArrayBuffer('11234567 9112345678911 345 789');
+
+  panner.setCursor(1, 3);
+  panner.setContent('a', content, [], 0);
+  panner.setDisplaySize(2, 10);
+  assertEqualsJSON({start: 1, end: 3}, panner.getCursor());
+  assertEqualsJSON({start: 1, end: 3}, panner.wrappedCursor_);
+
+  panner.setCursor(5, 10);
+  panner.setContent('a', content, [], 0);
+  assertEqualsJSON({start: 5, end: 10}, panner.getCursor());
+  assertEqualsJSON({start: 5, end: 11}, panner.wrappedCursor_);
+
+  panner.setCursor(9, 9);
+  panner.setContent('a', content, [], 0);
+  assertEqualsJSON({start: 9, end: 9}, panner.getCursor());
+  assertEqualsJSON({start: 10, end: 11}, panner.wrappedCursor_);
+});