ServiceWorker: Use mojo's data pipe for respondWith(stream)

third_party/WebKit/LayoutTests/http/tests/serviceworker/chromium/resources/slow-response.php

Index: third_party/WebKit/LayoutTests/http/tests/serviceworker/chromium/resources/slow-response.php
diff --git a/third_party/WebKit/LayoutTests/http/tests/serviceworker/chromium/resources/slow-response.php b/third_party/WebKit/LayoutTests/http/tests/serviceworker/chromium/resources/slow-response.php
new file mode 100644
index 0000000000000000000000000000000000000000..1b772caf6e87a6322babd7040af5e64c75974e2a
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/http/tests/serviceworker/chromium/resources/slow-response.php
@@ -0,0 +1,19 @@
+<?php
+function put_chunk($txt) {
+  echo sprintf("%x\r\n", strlen($txt));
+  echo "$txt\r\n";
+}
+
+header("Content-type: text/html; charset=UTF-8");
+header("Transfer-encoding: chunked");
+flush();
+
+for ($i = 0; $i < 10000; $i++) {
+  put_chunk("$i<br>");
+  ob_flush();
+  flush();
+  usleep(1000000);
+}
+echo "0\r\n\r\n";
+
+?>