Import //fetch from Web Platform Tests.

third_party/WebKit/LayoutTests/external/wpt/fetch/api/basic/scheme-data.js

+if (this.document === undefined) {
+  importScripts("/resources/testharness.js");
+  importScripts("../resources/utils.js");
+}
+
+function checkFetchResponse(url, data, mime, fetchMode, method) {
+  var cut = (url.length >= 40) ? "[...]" : "";
+  desc = "Fetching " + (method ? "[" + method + "] " : "") + url.substring(0, 40) + cut + " is OK";
+  var init = {"method": method || "GET"};
+  if (fetchMode) {
+    init.mode = fetchMode;
+    desc += " (" + fetchMode + ")";
+  }
+  promise_test(function(test) {
+    return fetch(url, init).then(function(resp) {
+      assert_equals(resp.status, 200, "HTTP status is 200");
+      assert_equals(resp.statusText, "OK", "HTTP statusText is OK");
+      assert_equals(resp.type, "basic", "response type is basic");
+      assert_equals(resp.headers.get("Content-Type"), mime, "Content-Type is " + resp.headers.get("Content-Type"));
+     return resp.text();
+    }).then(function(body) {
+        assert_equals(body, data, "Response's body is correct");
+    });
+  }, desc);
+}
+
+checkFetchResponse("data:,response%27s%20body", "response's body", "text/plain;charset=US-ASCII");
+checkFetchResponse("data:,response%27s%20body", "response's body", "text/plain;charset=US-ASCII", "same-origin");
+checkFetchResponse("data:,response%27s%20body", "response's body", "text/plain;charset=US-ASCII", "cors");
+checkFetchResponse("data:text/plain;base64,cmVzcG9uc2UncyBib2R5", "response's body", "text/plain");
+checkFetchResponse("data:image/png;base64,cmVzcG9uc2UncyBib2R5",
+                   "response's body",
+                   "image/png");
+checkFetchResponse("data:,response%27s%20body", "response's body", "text/plain;charset=US-ASCII", null, "POST");
+checkFetchResponse("data:,response%27s%20body", "response's body", "text/plain;charset=US-ASCII", null, "HEAD");
+
+function checkKoUrl(url, method, desc) {
+  var cut = (url.length >= 40) ? "[...]" : "";
+  desc = "Fetching [" + method + "] " + url.substring(0, 45) + cut + " is KO"
+  promise_test(function(test) {
+    return promise_rejects(test, new TypeError(), fetch(url, {"method": method}));
+  }, desc);
+}
+
+checkKoUrl("data:notAdataUrl.com", "GET");
+
+done();