Add a virtual beamforming audio device on ChromeOS.

content/renderer/media/media_stream_audio_processor_options.cc

Index: content/renderer/media/media_stream_audio_processor_options.cc
diff --git a/content/renderer/media/media_stream_audio_processor_options.cc b/content/renderer/media/media_stream_audio_processor_options.cc
index 1f875f9525e0d89317c614bd20c6ec6dd659cbae..79614dff3f133e70371b7250148a2cf2daaae17a 100644
--- a/content/renderer/media/media_stream_audio_processor_options.cc
+++ b/content/renderer/media/media_stream_audio_processor_options.cc
@@ -51,27 +51,29 @@ struct {
   const char* key;
   bool value;
 } const kDefaultAudioConstraints[] = {
-  { MediaAudioConstraints::kEchoCancellation, true },
-  { MediaAudioConstraints::kGoogEchoCancellation, true },
+    {MediaAudioConstraints::kEchoCancellation, true},
+    {MediaAudioConstraints::kGoogEchoCancellation, true},
 #if defined(OS_ANDROID) || defined(OS_IOS)
-  { MediaAudioConstraints::kGoogExperimentalEchoCancellation, false },
+    {MediaAudioConstraints::kGoogExperimentalEchoCancellation, false},
 #else
-  // Enable the extended filter mode AEC on all non-mobile platforms.
-  { MediaAudioConstraints::kGoogExperimentalEchoCancellation, true },
+    // Enable the extended filter mode AEC on all non-mobile platforms.
+    {MediaAudioConstraints::kGoogExperimentalEchoCancellation, true},
 #endif
-  { MediaAudioConstraints::kGoogAutoGainControl, true },
-  { MediaAudioConstraints::kGoogExperimentalAutoGainControl, true },
-  { MediaAudioConstraints::kGoogNoiseSuppression, true },
-  { MediaAudioConstraints::kGoogHighpassFilter, true },
-  { MediaAudioConstraints::kGoogTypingNoiseDetection, true },
-  { MediaAudioConstraints::kGoogExperimentalNoiseSuppression, false },
-  { MediaAudioConstraints::kGoogBeamforming, false },
+    {MediaAudioConstraints::kGoogAutoGainControl, true},
+    {MediaAudioConstraints::kGoogExperimentalAutoGainControl, true},
+    {MediaAudioConstraints::kGoogNoiseSuppression, true},
+    {MediaAudioConstraints::kGoogHighpassFilter, true},
+    {MediaAudioConstraints::kGoogTypingNoiseDetection, true},
+    {MediaAudioConstraints::kGoogExperimentalNoiseSuppression, false},
+    // Beamforming will only be enabled if we are also provided with a
+    // multi-microphone geometry.
+    {MediaAudioConstraints::kGoogBeamforming, false},

[ajm, 2015/08/26 01:55:09]

Disabled by default for now. I'll default enable in a focused follow-up.

 #if defined(OS_WIN)
-  { kMediaStreamAudioDucking, true },
+    {kMediaStreamAudioDucking, true},
 #else
-  { kMediaStreamAudioDucking, false },
+    {kMediaStreamAudioDucking, false},
 #endif
-  { kMediaStreamAudioHotword, false },
+    {kMediaStreamAudioHotword, false},
 };
 
 bool IsAudioProcessingConstraint(const std::string& key) {
@@ -393,10 +395,14 @@ void GetAecStats(webrtc::EchoCancellation* echo_cancellation,
 
 CONTENT_EXPORT std::vector<webrtc::Point> ParseArrayGeometry(
     const std::string& geometry_string) {
+  std::vector<webrtc::Point> geometry;
+  if (geometry_string.empty()) {
+    return geometry;
+  }
+
   const auto& tokens =
       base::SplitString(geometry_string, base::kWhitespaceASCII,
                         base::KEEP_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
-  std::vector<webrtc::Point> geometry;
   if (tokens.size() < 3 || tokens.size() % 3 != 0) {
     LOG(ERROR) << "Malformed geometry string: " << geometry_string;
     return geometry;