Mac Video Capture: expose --enable-avfoundation as tristate in chrome://flags

media/video/capture/mac/avfoundation_glue.mm

 // 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.
 
 #import "media/video/capture/mac/avfoundation_glue.h"
 
 #include <dlfcn.h>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 102 matching lines @@
 
   // AVFoundation is only available on OS Lion and above.
   if (!base::mac::IsOSLionOrLater())
     return false;
 
   // The force-qtkit flag takes precedence over enable-avfoundation.
   if (command_line->HasSwitch(switches::kForceQTKit))
     return false;
 
   // Next in precedence is the enable-avfoundation flag.
-  // TODO(mcasas,vrk): There should be 3 states of AVFoundation: user forced on,
-  // user forced off (i.e. force QTKit), and default (respect field trial).
-  // crbug.com/396764
   // TODO(vrk): Does this really need to be static?
   static bool should_enable_avfoundation =
       command_line->HasSwitch(switches::kEnableAVFoundation) ||
       base::FieldTrialList::FindFullName("AVFoundationMacVideoCapture")
           == "Enabled";
   // Try to load AVFoundation. Save result in static bool to avoid loading
   // AVFoundationBundle every call.
   static bool loaded_successfully = [AVFoundationBundle() load];
   return should_enable_avfoundation && loaded_successfully;
 }
@@ skipping 79 matching lines @@
 @implementation AVCaptureDeviceInputGlue
 
 + (CrAVCaptureDeviceInput*)deviceInputWithDevice:(CrAVCaptureDevice*)device
                                            error:(NSError**)outError {
   return [[AVFoundationGlue::AVFoundationBundle()
       classNamed:@"AVCaptureDeviceInput"] deviceInputWithDevice:device
                                                           error:outError];
 }
 
 @end  // @implementation AVCaptureDeviceInputGlue