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

tools/chrome_proxy/testserver/server.go

Index: tools/chrome_proxy/testserver/server.go
diff --git a/tools/chrome_proxy/testserver/server.go b/tools/chrome_proxy/testserver/server.go
index 698e45ce46d1c3cfc1e997ef4a4a604db4509729..3232f6dd96f3b5c8bd510e36510e0244edd254b6 100644
--- a/tools/chrome_proxy/testserver/server.go
+++ b/tools/chrome_proxy/testserver/server.go
@@ -35,12 +35,15 @@ import (
 	"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.
@@ -82,6 +85,18 @@ func defaultResponse(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// 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