* Electron version: 1.7.4
* Operating system: macOS Sierra

### Expected behavior

Load the PDF file correctly.

### Actual behavior

When I try to load something like http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1118&context=podimproveacad, the '&' symbol seems to interrupt the PDF Viewer to load the file.
![](http://i.imgur.com/RDSeY2u.png)

You can see that part of query string behind '&' get chopped, and I believe this is the reason why the PDF Viewer failed to load.

### How to reproduce

Clone the reproducible project at https://github.com/qazbnm456/electron-quick-start.
```
$ yarn # install packages
$ yarn run start # start the electron
```
atom/browser/atom_resource_dispatcher_host_delegate.cc
net::URLRequest* request,
    const base::FilePath& plugin_path,
    const std::string& mime_type,
    GURL* origin,
    std::string* payload) {
  const content::ResourceRequestInfo* info =
      content::ResourceRequestInfo::ForRequest(request);
  if (mime_type == "application/pdf" && info->IsMainFrame()) {
    *origin = GURL(kPdfViewerUIOrigin);
    content::BrowserThread::PostTask(
        BrowserThread::UI, FROM_HERE,
        base::Bind(&OnPdfResourceIntercepted, request->url(),
                   info->GetWebContentsGetterForRequest()));
    return true;
  }
  return false;
}
}