Inherit CSP when we inherit the security origin

This prevents attacks that use main window navigation to get out of the
existing csp constraints such as the related bug

Bug: 747847
Change-Id: I1e57b50da17f65d38088205b0a3c7c49ef2ae4d8
Reviewed-on: https://chromium-review.googlesource.com/592027
Reviewed-by: Mike West <mkwst@chromium.org>
Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#492333}
  virtual void BeginPrintMode(float width, float height) {
    DCHECK(!printed_page_width_);
    printed_page_width_ = width;
    printed_page_height_ = height;
    PrintContext::BeginPrintMode(printed_page_width_, height);
  }

  virtual void BeginPrintMode(float width, float height) {
    DCHECK(!printed_page_width_);
    printed_page_width_ = width;
    printed_page_height_ = height;
    PrintContext::BeginPrintMode(printed_page_width_, height);
  }
