Add a mimeHandler extension API.

chrome/test/data/extensions/api_test/mime_handler_view/embedded.js

 // Copyright 2014 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.
 
+'use strict';
+
 window.addEventListener('message', function(event) {
   // Echo the data back to the source window.
   event.source.postMessage(event.data, '*');
-}, false);
+}, false);
+
+var streamDetails;
+
+function fetchUrl(url) {
+  return new Promise(function(resolve, reject) {
+    var request = new XMLHttpRequest();
+    request.onreadystatechange = function() {
+      if (request.readyState == 4) {
+        resolve({
+          status: request.status,
+          data: request.responseText,
+        });
+      }
+    };
+    request.open('GET', streamDetails.streamUrl, true);
+    request.send();
+  });
+}
+
+var tests = [
+  function testBasic() {
+    chrome.test.assertEq(
+        'chrome-extension://oickdpebdnfbgkcaoklfcdhjniefkcji/testBasic.csv',
+        streamDetails.originalUrl);
+    chrome.test.assertEq('text/csv', streamDetails.mimeType);
+    chrome.test.assertTrue(streamDetails.tabId != -1);
+    chrome.test.assertFalse(streamDetails.embedded);
+
+    fetchUrl(streamDetails.streamUrl).then(function(response) {
+      chrome.test.assertEq(200, response.status);
+      chrome.test.assertEq('content to read\n', response.data);
+      chrome.test.succeed();
+    });
+  },
+
+  function testEmbedded() {
+    chrome.test.assertEq(
+        'chrome-extension://oickdpebdnfbgkcaoklfcdhjniefkcji/testEmbedded.csv',
+        streamDetails.originalUrl);
+    chrome.test.assertEq('text/csv', streamDetails.mimeType);
+    chrome.test.assertTrue(streamDetails.tabId != -1);
+    chrome.test.assertTrue(streamDetails.embedded);
+
+    fetchUrl(streamDetails.streamUrl).then(function(response) {
+      chrome.test.assertEq(200, response.status);
+      chrome.test.assertEq('content to read\n', response.data);
+      chrome.test.succeed();
+    });
+  },
+
+  function testAbort() {
+    chrome.mimeHandler.abortStream(function() {
+      fetchUrl(streamDetails.streamUrl).then(function(response) {
+        chrome.test.assertEq(404, response.status);
+        chrome.test.assertEq('', response.data);
+        chrome.test.succeed();
+      });
+    });
+  },
+];
+
+var testsByName = {};
+for (let i = 0; i < tests.length; i++) {
+  testsByName[tests[i].name] = tests[i];
+}
+
+chrome.mimeHandler.getStreamInfo(function(streamInfo) {
+  if (!streamInfo)
+    return;
+
+  var urlComponents = streamInfo.originalUrl.split('/');
+  var test = urlComponents[urlComponents.length - 1].split('.')[0];

[raymes, 2015/01/13 00:05:11]

nit: maybe just add a comment about which tests are run

[Sam McNally, 2015/01/13 05:30:08]

Done.

+  streamDetails = streamInfo;
+  if (testsByName[test])
+    chrome.test.runTests([testsByName[test]]);
+});