Implement Chrome Extension TabCapture API.

chrome/common/extensions/api/tab_capture.idl

+// 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.
+
+// An API for tab media streams.
+
+namespace tabCapture {
+
+  enum TabCaptureState {
+    requested,
+    pending,
+    active,
+    stopped,
+    error
+  };
+
+  dictionary CaptureInfo {
+    // The id of the tab whose status changed.
+    long tabId;
+
+    // The new capture status of the tab.
+    TabCaptureState status;
+  };
+
+  dictionary CaptureOptions {
+    boolean? audio;
+    boolean? video;
+  };
+
+  callback GetTabMediaCallback =
+      void ([instanceOf=LocalMediaStream] optional object stream);
+
+  callback GetCapturedTabsCallback =
+      void (CaptureInfo[] result);
+
+  interface Functions {
+    // Captures the visible area of the tab with the given tabId.
+    // Extensions must have the host permission for the given tab as well as
+    // the "tabs" permission to use this method.
+    // |tabId| : The tabId of the tab to capture.  Defaults to the active tab.
+    // |options| : Configures the returned media stream.
+    // |callback| : Callback with either the stream returned or null.
+    static void capture(optional long tabId,
+                        optional CaptureOptions options,
+                        GetTabMediaCallback callback);
+
+    // Returns a list of tabs that have requested capture or are being
+    // captured, i.e. status != stopped and status != cancelled.
+    // This allows extensions to inform the user that there is an existing
+    // tab capture that would prevent a new tab capture from succeeding (or
+    // to prevent redundant requests for the same tab).
+    static void getCapturedTabs(GetCapturedTabsCallback callback);
+
+  };
+
+  interface Events {
+    // Event fired when the capture status of a tab changes.
+    // This allows extension authors to keep track of the capture status of
+    // tabs to keep UI elements like page actions and infobars in sync.
+    static void onStatusChanged(CaptureInfo info);
+  };
+
+};