[WebSocket] Make arraybuffer test flexible about iteration and server address.

This patch changes the test to listen |searchParams| option so that
we can test it in various size from lightweight-for-check to heavyweight-for-accuracy.

Example:
$ content_shell receive-arraybuffer-1MBx100.html?iteration=3&server=ws://127.0.0.1:8002/
>
Connect to ws://127.0.0.1:8002/
Running 3 times
Ignoring warm-up run (346.07608397871 MB/s)
349.01482119459 MB/s
332.869505903946 MB/s
286.404642021716 MB/s
Description: Measure performance of receiving 1MB array 100 times.


Bug: 954000
Change-Id: Idc0365c97e6a659f0d91e8e57f6c789407b06739
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1669149
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Reviewed-by: Hayato Ito <hayato@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671995}

third_party/blink/perf_tests/websocket/receive-arraybuffer-1MBx100.html

@@ -11,8 +11,13 @@
 // $ npm start
 // $ python ../../../../tools/perf/run_benchmark run blink_perf --browser=canary --test-path=websocket\receive-arraybuffer-1MBx100.html
 
+const params = (new URL(document.location)).searchParams;
+const server = params.get("server") || "ws://127.0.0.1:8001/";
+PerfTestRunner.log("Connect to " + server);
+const iteration = params.get("iteration") || 6;
+
 async function runTestCase() {
-  const ws = new WebSocket("ws://127.0.0.1:8001/");
+  const ws = new WebSocket(server);
   ws.binaryType = "arraybuffer";
   const onOpen = new Promise(resolve => {
     ws.onopen = () => {
@@ -42,7 +47,7 @@ PerfTestRunner.startMeasureValuesAsync({
   run: async function() {
     while (!isDone) await runTestCase();
   },
-  iterationCount: 6,
+  iterationCount: iteration,
 });
 </script>
 </body>