refactor EnumerateDevices to make it a persistent request.

content/common/media/media_stream_options.cc

 // 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 "content/common/media/media_stream_options.h"
 
 namespace media_stream {
 
 // static
 const int StreamDeviceInfo::kNoId = -1;
 
 StreamDeviceInfo::StreamDeviceInfo()
     : stream_type(content::MEDIA_STREAM_DEVICE_TYPE_NO_SERVICE),
       in_use(false),
       session_id(kNoId) {}
 
 StreamDeviceInfo::StreamDeviceInfo(MediaStreamType service_param,
                                    const std::string& name_param,
                                    const std::string& device_param,
                                    bool opened)
     : stream_type(service_param),
       name(name_param),
       device_id(device_param),
       in_use(opened),
       session_id(kNoId) {}
 
+bool StreamDeviceInfo::operator==(const StreamDeviceInfo &other) const {

[scherkus (not reviewing), 2012/08/02 00:14:19]

& with type name

[wjia(left Chromium), 2012/08/02 22:15:27]

Done.

+  return stream_type == other.stream_type &&
+         name == other.name &&

[scherkus (not reviewing), 2012/08/02 00:14:19]

nit: this should be 4 space indent here + below (the same-level indent only
applies to when stuff is inside parentheses, otherwise it's a 4 space indent)

[wjia(left Chromium), 2012/08/02 22:15:27]

Done.

+         device_id == other.device_id &&
+         in_use == other.in_use &&
+         session_id == other.session_id;
+}
+
 }  // namespace media_stream