Added a chrome flag to enable Delay Agnostic AEC in WebRTC

content/renderer/media/media_stream_audio_processor.cc

Index: content/renderer/media/media_stream_audio_processor.cc
diff --git a/content/renderer/media/media_stream_audio_processor.cc b/content/renderer/media/media_stream_audio_processor.cc
index 81dec9130df16858a8e525190bb4c72f63d4515c..d42e22e18d83650f9cdb93e790e1d0d2e5758382 100644
--- a/content/renderer/media/media_stream_audio_processor.cc
+++ b/content/renderer/media/media_stream_audio_processor.cc
@@ -4,11 +4,13 @@
 
 #include "content/renderer/media/media_stream_audio_processor.h"
 
+#include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #if defined(OS_MACOSX)
 #include "base/metrics/field_trial.h"
 #endif
 #include "base/metrics/histogram.h"
+#include "content/public/common/content_switches.h"
 #include "content/renderer/media/media_stream_audio_processor_options.h"
 #include "content/renderer/media/rtc_media_constraints.h"
 #include "content/renderer/media/webrtc_audio_device_impl.h"
@@ -73,6 +75,20 @@ void RecordProcessingState(AudioTrackProcessingStates state) {
                             state, AUDIO_PROCESSING_MAX);
 }
 
+bool isDelayAgnosticAecEnabled() {
+#if defined(OS_MACOSX)

[perkj_chrome, 2015/01/09 07:37:08]

Are these if defs necessary? How about:

base::CommandLine* command_line =base::CommandLine::ForCurrentProcess();
if (command_line->HasSwitch(switches::kEnableDelayAgnosticAec))
  return true;

const std::string group_name =
  base::FieldTrialList::FindFullName("NoReportedDelayOnMac");
return (group_name == "Enabled");

[bjornv, 2015/01/10 10:08:40]

You have to acquire the Finch group name first, but not evaluate the result if
you want to exclude flag users from the stats; See go/finch-and-flags

I kept the defs since it was under def before, but how about this change?

+  const std::string group_name =
+      base::FieldTrialList::FindFullName("NoReportedDelayOnMac");
+#endif
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kEnableDelayAgnosticAec))
+    return true;
+#if defined(OS_MACOSX)
+  return (group_name == "Enabled");
+#else
+  return false;
+#endif
+}
 }  // namespace
 
 // Wraps AudioBus to provide access to the array of channel pointers, since this
@@ -462,10 +478,8 @@ void MediaStreamAudioProcessor::InitializeAudioProcessingModule(
     config.Set<webrtc::DelayCorrection>(new webrtc::DelayCorrection(true));
   if (goog_experimental_ns)
     config.Set<webrtc::ExperimentalNs>(new webrtc::ExperimentalNs(true));
-#if defined(OS_MACOSX)
-  if (base::FieldTrialList::FindFullName("NoReportedDelayOnMac") == "Enabled")
+  if (isDelayAgnosticAecEnabled())
     config.Set<webrtc::ReportedDelay>(new webrtc::ReportedDelay(false));
-#endif
 
   // Create and configure the webrtc::AudioProcessing.
   audio_processing_.reset(webrtc::AudioProcessing::Create(config));