title: How to pass 'Authorization' header value in OAuth 2.0 with Google APIs
body: <p>I am trying to access Google's APIs with OAuth 1.0 and 2.0 in both cases I need to fill Authorization field in the headers with value 'OAuth' followed by access token. I tried following method, but Google throws me an error saying there is problem in Authorization header values. I am using Python-Tornado</p>
  
  <pre><code>additional_headers = {
          "Authorization": "OAuth "+GoogleOAuth2Mixin.access_token,
          "Accept-Encoding": None
      }
      h = httputil.HTTPHeaders()
      h.parse_line("Authorization: OAuth "+GoogleOAuth2Mixin.access_token)
      request = httpclient.HTTPRequest(self._USER_INFO_URL+"?access_token="+GoogleOAuth2Mixin.access_token, method="GET", headers=h)
      self.httpclient_instance.fetch(
          request,
          self.async_callback(callback)
      )
  </code></pre>
  
  <p>I tried using both methods, by passing header 'h' and 'additional_headers', but it doesn't work. What is an accurate method? </p>