Code: void MimeHandlerViewContainer::OnReady() {
  if (!render_frame() || !is_embedded_)
    return;

  blink::WebLocalFrame* frame = render_frame()->GetWebFrame();

  blink::WebAssociatedURLLoaderOptions options;
  DCHECK(!loader_);
  loader_.reset(frame->CreateAssociatedURLLoader(options));

   blink::WebURLRequest request(original_url_);
   request.SetRequestContext(blink::WebURLRequest::kRequestContextObject);
   loader_->LoadAsynchronously(request, this);
 }

Vulnerability Type: 
CWE ID: CWE-20
Summary: A lack of CORS checks, after a Service Worker redirected to a cross-origin PDF, in Service Worker in Google Chrome prior to 66.0.3359.117 allowed a remote attacker to leak limited cross-origin data via a crafted HTML page.
Commit Message: Skip Service workers in requests for mime handler plugins

BUG=808838
TEST=./browser_tests --gtest_filter=*/ServiceWorkerTest.MimeHandlerView*

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: I82e75c200091babbab648a04232db47e2938d914
Reviewed-on: https://chromium-review.googlesource.com/914150
Commit-Queue: Rob Wu <rob@robwu.nl>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537386}