Make an HTTP requestor Chrome extension for meek-client

[dcf]

Like in #11183, make an extension for Chrome/Chromium that makes HTTP requests on behalf of another program.

[dcf]

Chang started doing this at ​https://github.com/changlan/meek/tree/chrome (and copied to ​https://gitweb.torproject.org/pluggable-transports/meek.git/shortlog/refs/heads/chrome). It is broken into two parts: and app and an extension, because extensions aren't allowed to open listening sockets in Chrome. It goes like this:

meek-client ←(socket)→ app ←(message)→ extension ←(HTTPS)→ www.google.com

According to ​https://developer.chrome.com/extensions/webRequest, it's not supposed to be possible to modify the Host header. But apparently it works. ​https://code.google.com/p/chromium/issues/detail?id=158073 is the bug report noting the discrepancy.

[clan]

The webRequest API does not handle SPDY connection properly. It does not change the HTTP header when SPDY is enabled. To use the extension you need to disable SPDY in Chrome, so that Chrome will connect to Google using HTTP rather SPDY. Since the documentation (​https://developer.chrome.com/extensions/webRequest) does not mention anything about SPDY, it should behave consistently. It is probably a bug.

To disable SPDY, you can run Chrome with the argument --use-spdy=off.

[dcf]

Adding a link to the upstream Chromium issue from comment:3:

• WebRequest cannot set Host header for SPDY requests
  ​https://code.google.com/p/chromium/issues/detail?id=364319

[dcf]

I ​removed the Chrome extension from the source code just now. I think it hasn't been used in a while and it isn't getting maintenance. If we need to get it back, the last commit that had it was ​b60dc093c98c650f3a8ab1445da8b9185791cbcc.