Mac Video Capture: Connect AVFoundation for Canary and Developer builds. Other channels unaffected.

BUG=408089

Review URL: https://codereview.chromium.org/511863002

Cr-Commit-Position: refs/heads/master@{#292161}

chrome/browser/media/media_capture_devices_dispatcher.cc

@@ -276,6 +276,19 @@ MediaCaptureDevicesDispatcher::MediaCaptureDevicesDispatcher()
   notifications_registrar_.Add(
       this, content::NOTIFICATION_WEB_CONTENTS_DESTROYED,
       content::NotificationService::AllSources());
+
+  // AVFoundation is used for video/audio device monitoring and video capture in
+  // Mac. Experimentally, connect it in Canary and Unknown (developer builds).
+#if defined(OS_MACOSX)
+  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kForceQTKit)) {
+    if (channel == chrome::VersionInfo::CHANNEL_CANARY ||
+        channel == chrome::VersionInfo::CHANNEL_UNKNOWN) {
+      CommandLine::ForCurrentProcess()->AppendSwitch(
+          switches::kEnableAVFoundation);
+    }
+  }
+#endif
 }
 
 MediaCaptureDevicesDispatcher::~MediaCaptureDevicesDispatcher() {}