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 {

[tommi (sloooow) - chröme, 2012/08/03 09:10:35]

nit: Change this method to IsEqual() (we don't override operators except for
special cases)

[wjia(left Chromium), 2012/08/03 21:53:45]

This overloading is needed for StreamDeviceInfoArray which is typedef'ed as
std::vector<StreamDeviceInfo>. In MediaStreamManager::DevicesEnumerated, the
incoming devices are compared against cached devices.

[tommi (sloooow) - chröme, 2012/08/04 09:27:08]

You can use std::equal instead.  See for example:
http://code.google.com/searchframe#OAMlx_jo-ck/src/chrome/browser/policy/poli...

[wjia(left Chromium), 2012/08/07 23:16:34]

Done.

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