If a page shows a popup, end fullscreen.

This was implemented in Blink r159834, but it is susceptible
to a popup/fullscreen race. This CL reverts that implementation
and re-implements it in WebContents.

BUG=752003
TEST=WebContentsImplBrowserTest.PopupsFromJavaScriptEndFullscreen

Change-Id: Ia345cdeda273693c3231ad8f486bebfc3d83927f
Reviewed-on: https://chromium-review.googlesource.com/606987
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Cr-Commit-Position: refs/heads/master@{#498171}
void WebContentsImpl::SetAccessibilityMode(ui::AXMode mode) {
  if (mode == accessibility_mode_)
    return;

  if (IsNeverVisible())
    return;

  accessibility_mode_ = mode;

  for (FrameTreeNode* node : frame_tree_.Nodes()) {
    UpdateAccessibilityModeOnFrame(node->current_frame_host());
    RenderFrameHost* pending_frame_host =
        node->render_manager()->pending_frame_host();
    if (pending_frame_host)
      UpdateAccessibilityModeOnFrame(pending_frame_host);
  }
}

void WebContentsImpl::SetAccessibilityMode(ui::AXMode mode) {
  if (mode == accessibility_mode_)
    return;

  if (IsNeverVisible())
    return;

  accessibility_mode_ = mode;

  for (FrameTreeNode* node : frame_tree_.Nodes()) {
    UpdateAccessibilityModeOnFrame(node->current_frame_host());
    RenderFrameHost* pending_frame_host =
        node->render_manager()->pending_frame_host();
    if (pending_frame_host)
      UpdateAccessibilityModeOnFrame(pending_frame_host);
  }
}
