Add Open my editor

tools/chrome_extensions/open_my_editor/ext/cs-content.js

+// Copyright 2017 Google Inc.
+//
+// Copyright 2017 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.
+
+// For cs.chromium.org
+
+let line = 0;
+
+document.addEventListener("mousedown", (event) => {
+  //right click

[watk, 2017/03/02 23:13:49]

Proper punctuation. Space after //.

+  if (event.button == 2) {
+    let element = event.target;
+    while (element != null && element.tagName == "SPAN") {
+      if (element.className == "stx-line") {
+        line = parseInt(element.id.split("_")[1]);
+        break;
+      } else {
+        element = element.parentElement;
+      }
+    }
+  }
+}, true);
+
+chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
+  if (request == "getLine") {
+    sendResponse({ line: line });
+  }
+});