### Preflight Checklist

* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

### Issue Details

* **Electron Version:**
  * v10.1.2
* **Operating System:**
  * Windows 10 (1809)
* **Last Known Working Electron version:**
  * 5.0.1  (have not tested others)

### Expected Behavior
From a console, start electron with a remote-debugging-port.  E.g. 

```
$ electron --remote-debugging-port=9092
```

Now navigate to localhost:9092. We would expect to see devtools remotely attached.

### Actual Behavior
A scrambled mess appears. (output is shortened below)
```��Tmo�0��.......```

### To Reproduce
```
$ electron --remote-debugging-port=9092
```

### Additional Information
If you navigate to `http://localhost:9092/json/list`, and then scrape the URL out of `devtoolsFrontendUrl`, you can access them that way. Although this works, it is somewhat of a chore.

shell/browser/ui/devtools_manager_delegate.cc
#include "content/public/browser/devtools_socket_factory.h"
#include "content/public/browser/favicon_status.h"
#include "content/public/browser/navigation_entry.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/url_constants.h"
#include "content/public/common/user_agent.h"
#include "electron/grit/electron_resources.h"
#include "net/base/net_errors.h"
#include "net/socket/stream_socket.h"
#include "net/socket/tcp_server_socket.h"
#include "shell/browser/browser.h"
#include "shell/common/electron_paths.h"
#include "third_party/inspector_protocol/crdtp/dispatch.h"
#include "ui/base/resource/resource_bundle.h"
namespace electron {
namespace {
class TCPServerSocketFactory : public content::DevToolsSocketFactory {
 public:
  TCPServerSocketFactory(const std::string& address, int port)
      : address_(address), port_(port) {}
 private:
  
  std::unique_ptr<net::ServerSocket> CreateForHttpServer() override {
    std::unique_ptr<net::ServerSocket> socket(
        new net::TCPServerSocket(nullptr, net::NetLogSource()));
    if (socket->ListenWithAddressAndPort(address_, port_, 10) != net::OK)
      return std::unique_ptr<net::ServerSocket>();
    return socket;
  }
  std::unique_ptr<net::ServerSocket> CreateForTethering(