Implement Chrome Extension TabCapture API.

chrome/renderer/resources/extensions/experimental.tab_capture_custom_bindings.js

+// Copyright (c) 2012 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.
+
+// Custom bindings for the Tab Capture API.
+
+var tabCaptureNatives = requireNative('experimental_tabCapture');
+var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
+
+chromeHidden.registerCustomHook('experimental.tabCapture',
+                                function(bindingsAPI, extensionId) {
+  var apiFunctions = bindingsAPI.apiFunctions;
+
+  apiFunctions.setCustomCallback('getTabMedia',
+                                 function(name, request, response) {
+    if (response && request.callback) {
+      var callback = request.callback;
+      var successFunc = function(stream) {
+        callback(stream);
+      };
+      var errorFunc = function() {
+        callback(null);
+      };
+      var videoConstraints = false;
+      var audioConstraints = false;
+
+      // TODO(justinlin): Merge with other constraints when they land.
+      if (response.options.video) {
+        videoConstraints = {
+          mandatory: {
+            chromeMediaSource: 'tab',
+            chromeMediaSourceId: response.deviceId
+          }
+        };
+      }
+
+      if (response.options.audio) {
+        audioConstraints = {
+          mandatory: {
+            chromeMediaSource: 'tab',
+            chromeMediaSourceId: response.deviceId
+          }
+        };
+      }
+
+      var options = {};
+      options.video = videoConstraints;
+      options.audio = audioConstraints;
+
+      navigator.webkitGetUserMedia(options, successFunc, errorFunc);
+    } else {
+      request.callback();
+    }
+    request.callback = null;
+  });
+});