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}
void DocumentLoader::ReplaceDocumentWhileExecutingJavaScriptURL(
    const KURL& url,
    Document* owner_document,
    bool should_reuse_default_view,
    const String& source) {
  InstallNewDocument(url, owner_document, should_reuse_default_view, MimeType(),
                     writer_ ? writer_->Encoding() : g_empty_atom,
                     InstallNewDocumentReason::kJavascriptURL,
                     kForceSynchronousParsing, NullURL());
  if (!source.IsNull())
    writer_->AppendReplacingData(source);
  EndWriting();
}

void DocumentLoader::ReplaceDocumentWhileExecutingJavaScriptURL(
    const KURL& url,
    Document* owner_document,
    bool should_reuse_default_view,
    const String& source) {
  InstallNewDocument(url, owner_document, should_reuse_default_view, MimeType(),
                     writer_ ? writer_->Encoding() : g_empty_atom,
                     InstallNewDocumentReason::kJavascriptURL,
                     kForceSynchronousParsing, NullURL());
  if (!source.IsNull())
    writer_->AppendReplacingData(source);
  EndWriting();
}
