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

content/renderer/media/media_stream_audio_processor_options.cc

 // Copyright 2013 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/renderer/media/media_stream_audio_processor_options.h"
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "base/strings/utf_string_conversions.h"
+#include "content/common/media/media_stream_options.h"
 #include "content/renderer/media/rtc_media_constraints.h"
 #include "media/audio/audio_parameters.h"
 #include "third_party/WebKit/public/platform/WebMediaConstraints.h"
 #include "third_party/libjingle/source/talk/app/webrtc/mediaconstraintsinterface.h"
 #include "third_party/webrtc/modules/audio_processing/include/audio_processing.h"
 
 namespace content {
 
 namespace {
 
@@ skipping 13 matching lines @@
   { webrtc::MediaConstraintsInterface::kAutoGainControl,
     webrtc::MediaConstraintsInterface::kValueTrue },
   { webrtc::MediaConstraintsInterface::kExperimentalAutoGainControl,
     webrtc::MediaConstraintsInterface::kValueTrue },
   { webrtc::MediaConstraintsInterface::kNoiseSuppression,
     webrtc::MediaConstraintsInterface::kValueTrue },
   { webrtc::MediaConstraintsInterface::kHighpassFilter,
     webrtc::MediaConstraintsInterface::kValueTrue },
   { webrtc::MediaConstraintsInterface::kTypingNoiseDetection,
     webrtc::MediaConstraintsInterface::kValueTrue },
+#if defined(OS_WIN)
+  { content::kMediaStreamAudioDucking,
+    webrtc::MediaConstraintsInterface::kValueTrue },
+#endif
 };
 
 } // namespace
 
 void ApplyFixedAudioConstraints(RTCMediaConstraints* constraints) {
   for (size_t i = 0; i < ARRAYSIZE_UNSAFE(kDefaultAudioConstraints); ++i) {
     bool already_set_value;
     if (!webrtc::FindConstraint(constraints, kDefaultAudioConstraints[i].key,
                                 &already_set_value, NULL)) {
+      // TODO(tommi): This adds the default constraints to the 'mandatory'
+      // section but it might make more sense to add these to the optional
+      // section since if for whatever reason the default implied constraints
+      // aren't supported on some platform then we should not fail the
+      // getUserMedia call.  'kMediaStreamAudioDucking' is an example where
+      // it is not supported on XP but is supported on newer versions.
       constraints->AddMandatory(kDefaultAudioConstraints[i].key,
           kDefaultAudioConstraints[i].value, false);
     } else {
       DVLOG(1) << "Constraint " << kDefaultAudioConstraints[i].key
                << " already set to " << already_set_value;
     }
   }
 }
 
 bool NeedsAudioProcessing(const blink::WebMediaConstraints& constraints,
@@ skipping 99 matching lines @@
   const webrtc::GainControl::Mode mode = webrtc::GainControl::kFixedDigital;
 #else
   const webrtc::GainControl::Mode mode = webrtc::GainControl::kAdaptiveAnalog;
 #endif
   int err = audio_processing->gain_control()->set_mode(mode);
   err |= audio_processing->gain_control()->Enable(true);
   CHECK_EQ(err, 0);
 }
 
 }  // namespace content