Code: void RenderWidgetHostImpl::WasShown(const ui::LatencyInfo& latency_info) {
  if (!is_hidden_)
    return;

  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::WasShown");
  is_hidden_ = false;
 
  if (new_content_rendering_timeout_ &&
      new_content_rendering_timeout_->IsRunning()) {
    new_content_rendering_timeout_->Stop();
    ClearDisplayedGraphics();
  }
 
   SendScreenRects();
   RestartHangMonitorTimeoutIfNecessary();

  bool needs_repainting = true;
  needs_repainting_on_restore_ = false;
  Send(new ViewMsg_WasShown(routing_id_, needs_repainting, latency_info));

  process_->WidgetRestored();

  bool is_visible = true;
  NotificationService::current()->Notify(
      NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
      Source<RenderWidgetHost>(this),
      Details<bool>(&is_visible));

  WasResized();
}

Vulnerability Type: 
CWE ID: 
Summary: Lack of clearing the previous site before loading alerts from a new one in Blink in Google Chrome prior to 67.0.3396.62 allowed a remote attacker to perform domain spoofing via a crafted HTML page.
Commit Message: Force a flush of drawing to the widget when a dialog is shown.

BUG=823353
TEST=as in bug

Change-Id: I5da777068fc29c5638ef02d50e59d5d7b2729260
Reviewed-on: https://chromium-review.googlesource.com/971661
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544518}