Make tab capture media stream requests verify that the request came from extension API

chrome/common/extensions/request_media_access_permission_helper.cc

Index: chrome/common/extensions/request_media_access_permission_helper.cc
diff --git a/chrome/common/extensions/request_media_access_permission_helper.cc b/chrome/common/extensions/request_media_access_permission_helper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c0c671d7b091c52a3d64ab828cd5a68b02577d20
--- /dev/null
+++ b/chrome/common/extensions/request_media_access_permission_helper.cc
@@ -0,0 +1,44 @@
+// 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.
+
+#include "chrome/common/extensions/request_media_access_permission_helper.h"
+
+namespace extensions {
+
+// static
+void RequestMediaAccessPermissionHelper::AuthorizeRequest(
+    const content::MediaStreamRequest* request,
+    const content::MediaResponseCallback& callback,
+    bool allow_audio,
+    bool allow_video,
+    bool allow_tab_media) {
+  content::MediaStreamDevices devices;
+
+  bool accepted_an_audio_device = false;
+  bool accepted_a_video_device = false;
+  for (content::MediaStreamDeviceMap::const_iterator it =
+       request->devices.begin(); it != request->devices.end(); ++it) {
+    if (!accepted_an_audio_device &&
+        content::IsAudioMediaType(it->first) &&
+        !it->second.empty() &&
+        ((it->first == content::MEDIA_DEVICE_AUDIO_CAPTURE && allow_audio) ||
+         (it->first == content::MEDIA_TAB_AUDIO_CAPTURE && allow_tab_media))) {
+      devices.push_back(it->second.front());
+      accepted_an_audio_device = true;
+    } else if (!accepted_a_video_device &&
+               content::IsVideoMediaType(it->first) &&
+               !it->second.empty() &&
+               ((it->first == content::MEDIA_DEVICE_VIDEO_CAPTURE &&
+                 allow_video) ||
+                (it->first == content::MEDIA_TAB_VIDEO_CAPTURE &&
+                 allow_tab_media))) {
+      devices.push_back(it->second.front());
+      accepted_a_video_device = true;
+    }
+  }
+
+  callback.Run(devices);
+}
+
+}  // namespace extensions