support video device enumeration from renderer process.

content/renderer/media/media_stream_impl_stub.cc

Index: content/renderer/media/media_stream_impl_stub.cc
===================================================================
--- content/renderer/media/media_stream_impl_stub.cc	(revision 118766)
+++ content/renderer/media/media_stream_impl_stub.cc	(working copy)
@@ -79,3 +79,20 @@
 void MediaStreamImpl::OnAudioDeviceFailed(const std::string& label,
                                           int index) {
 }
+
+void MediaStreamImpl::OnDevicesEnumerated(
+    int request_id,
+    const media_stream::StreamDeviceInfoArray& device_array) {
+}
+
+void MediaStreamImpl::OnDevicesEnumerationFailed(int request_id) {
+}
+
+void MediaStreamImpl::OnDeviceOpened(
+    int request_id,
+    const std::string& label,
+    const media_stream::StreamDeviceInfo& video_device) {
+}
+
+void MediaStreamImpl::OnDeviceOpenFailed(int request_id) {
+}