Chrome Version       : 61.0.3124.4
OS Version: OS X 10.12.5

1. Open chrome://version and enable voiceover
2. Connect to Chrome in Instruments with the leak checker
2a. (Record and stop then wait for a bit while the symbol cache loads), then:
3. Record (again) while navigating chrome://version using Ctrl+Alt+arrows


(more complex navigations might trigger more leaks)


There are 3 leaks identified (multiple times; once for each VoiceOver navigation). All stacks are under -[BrowserAccessibilityCocoa accessibilityAttributeValue:forParameter:]

1. The `new AXPositionType()` called via CreateTextMarker(position->CreatePreviousLineStartPosition()) to satisfy AXPreviousLineStartTextMarkerForTextMarker. I suspect the .release() in CreateTextMarker() is the cause of this one:

  static AXPositionInstance CreateTextPosition(int tree_id,
                                               int32_t anchor_id,
                                               int text_offset,
                                               AXTextAffinity affinity) {
    AXPositionInstance new_position(new AXPositionType());
    new_position->Initialize(AXPositionKind::TEXT_POSITION, tree_id, anchor_id,
                             INVALID_INDEX, text_offset, affinity);
    return new_position;
  }



2. and 3. are the two calls to `AXTextMarkerCreate` made to satisfy AXTextMarkerRangeForUIElement in 

id CreateTextMarkerRange(const AXPlatformRange range) {
  AXTextMarkerRef start_marker = AXTextMarkerCreate(
      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(range.anchor()),
      sizeof(AXPlatformPosition));
  AXTextMarkerRef end_marker = AXTextMarkerCreate(
      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(range.focus()),
      sizeof(AXPlatformPosition));
  AXTextMarkerRangeRef marker_range =
      AXTextMarkerRangeCreate(kCFAllocatorDefault, start_marker, end_marker);
  return static_cast<id>(
      base::mac::CFTypeRefToNSObjectAutorelease(marker_range));
}


For 2. and 3., it's harder to tell the source of the leak. I'll see if I can make it go away.
 

Deleted: Screen Shot 2017-06-22 at 2.08.58 pm.png 156 KB

	Screen Shot 2017-06-22 at 2.08.58 pm.png 156 KB View Download