Add Open my editor

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

Index: tools/chrome_extensions/open_my_editor/ext/cs-content.js
diff --git a/tools/chrome_extensions/open_my_editor/ext/cs-content.js b/tools/chrome_extensions/open_my_editor/ext/cs-content.js
new file mode 100644
index 0000000000000000000000000000000000000000..7df1b85b8dab838558c602ef49ce9a3f7a840147
--- /dev/null
+++ b/tools/chrome_extensions/open_my_editor/ext/cs-content.js
@@ -0,0 +1,28 @@
+// 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
+  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});
+  }
+});