Added integration test to Chrome Proxy to verify direct connection on remote site timeout

tools/chrome_proxy/testserver/server.go

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Test server to facilitate the data reduction proxy Telemetry tests.
 //
 // The server runs at http://chromeproxy-test.appspot.com/. Please contact
 // people in OWNERS for server issues.
 //
 // For running an AppEngine Go server, see:
@@ skipping 17 matching lines @@
 import (
         "bytes"
         "encoding/base64"
         "encoding/json"
         "errors"
         "fmt"
         "io"
         "net/http"
         "os"
         "strconv"
+        "strings"
+        "time"
 )
 
 func init() {
         http.HandleFunc("/requestHeader", requestHeader)
         http.HandleFunc("/resource", resource)
         http.HandleFunc("/default", defaultResponse)
+        http.HandleFunc("/blackhole", blackholeProxy)
 }
 
 // requestHander returns request headers in response body as text.
 func requestHeader(w http.ResponseWriter, r *http.Request) {
         r.Header.Write(w)
 }
 
 // resource returns the content of a data file specified by "r=" query as the response body.
 // The response could be overridden by request queries.
 // See parseOverrideQuery.
@@ skipping 21 matching lines @@
 func defaultResponse(w http.ResponseWriter, r *http.Request) {
         wroteBody, err := applyOverride(w, r)
         if err != nil {
                 return
         }
         if !wroteBody {
                 w.Write([]byte("ok"))
         }
 }
 
+// delay longer than 30s test failure threshold to any request coming from the

[sclittle, 2016/08/09 21:31:32]

nit: looking at the rest of the file, it looks like function comments start with
the function name, then a short description of what it does in complete
sentences (e.g. terminated by periods or other sentence-enders). Could you make
this comment match the others?

[Robert Ogden, 2016/08/09 21:56:22]

Done.

+// proxy, but respond immediately to any other request
+func blackholeProxy(w http.ResponseWriter, r *http.Request) {
+        if strings.Contains(r.Header.Get("via"), "Chrome-Compression-Proxy") {
+                // causes timeout on client, will then use direct instead

[sclittle, 2016/08/09 21:31:32]

nit: Could you capitalize the first word in this sentence and add a period at
the end?

[Robert Ogden, 2016/08/09 21:56:22]

Done.

+                time.Sleep(60 * time.Second);

[sclittle, 2016/08/09 21:31:32]

What is actually causing the bypass? Are you sure it's the client that's timing
out, and not the server (e.g. appengine), or the proxy?

If you are sure, could you explain in more detail what's happening here, e.g.
the path of the request, and at what point the timeout/bypass happens?

[Robert Ogden, 2016/08/09 21:56:22]

Done.

+                w.Write([]byte("You are proxy"));
+        } else {
+                w.Write([]byte("You are direct"));
+        }
+}
+
 type override struct {
         status int
         header http.Header
         body   io.Reader
 }
 
 // parseOverrideQuery parses the queries in r and returns an override.
 // It supports the following queries:
 //   "respStatus": an integer to override response status code;
 //   "respHeader": base64 encoded JSON data to override the response headers;
@@ skipping 59 matching lines @@
         return false, nil
 }
 
 func writeFromFile(w io.Writer, filename string) (int64, error) {
         f, err := os.Open(filename)
         if err != nil {
                 return 0, err
         }
         return io.Copy(w, f)
 }