Add basic support for "googDucking" to getUserMedia on Windows.

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"
 
 #include "base/logging.h"
 
 namespace content {
 
 const char kMediaStreamSource[] = "chromeMediaSource";
 const char kMediaStreamSourceId[] = "chromeMediaSourceId";
 const char kMediaStreamSourceInfoId[] = "sourceId";
 const char kMediaStreamSourceTab[] = "tab";
 const char kMediaStreamSourceScreen[] = "screen";
 const char kMediaStreamSourceDesktop[] = "desktop";
 const char kMediaStreamSourceSystem[] = "system";
 const char kMediaStreamRenderToAssociatedSink[] =
     "chromeRenderToAssociatedSink";
+// The prefix of this constant is 'goog' to match with other getUserMedia
+// constraints for audio.
+const char kMediaStreamAudioDucking[] = "googDucking";

[DaleCurtis, 2014/02/05 22:15:43]

Is this a web facing attribute?  I'm not familiar with this code.

[tommi (sloooow) - chröme, 2014/02/06 11:50:34]

Yes, these are constraints that can be passed to getUserMedia.
Here are more audio constraints as an example, but these constants are different
in the respect that they are currently implemented in libjingle (in the process
of being moved over to Chrome):
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/libjin...

The constant just above this new one, kMediaStreamRenderToAssociatedSink, is
another example but it uses the 'chrome' prefix which has been decided is not a
good thing since it introduces a new namespace.

[DaleCurtis, 2014/02/06 19:19:59]

Do you need to make any FYI / PSA announcements on blink-dev / chromium-dev or
what not for this change then?  See what VP9 did here:

https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/omm_XzZ7mMg/WB...

 
 namespace {
 
 bool GetFirstConstraintByName(const StreamOptions::Constraints& constraints,
                               const std::string& name,
                               std::string* value) {
   for (StreamOptions::Constraints::const_iterator it = constraints.begin();
       it != constraints.end(); ++it ) {
     if (it->name == name) {
       *value = it->value;
@@ skipping 88 matching lines @@
 }
 
 // static
 bool StreamDeviceInfo::IsEqual(const StreamDeviceInfo& first,
                                const StreamDeviceInfo& second) {
   return first.device.IsEqual(second.device) &&
       first.session_id == second.session_id;
 }
 
 }  // namespace content