Added code for AVFoundation Finch Experiment enabling

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"
 #include "base/mac/mac_util.h"
+#include "base/metrics/field_trial.h"
 #include "media/base/media_switches.h"
 
 namespace {
 
 // This class is used to retrieve AVFoundation NSBundle and library handle. It
 // must be used as a LazyInstance so that it is initialised once and in a
 // thread-safe way. Normally no work is done in constructors: LazyInstance is
 // an exception.
 class AVFoundationInternal {
  public:
@@ skipping 27 matching lines @@
 static NSString* ReadNSStringPtr(const char* symbol) {
   NSString** string_pointer = reinterpret_cast<NSString**>(
       dlsym(AVFoundationGlue::AVFoundationLibraryHandle(), symbol));
   DCHECK(string_pointer) << dlerror();
   return *string_pointer;
 }
 
 }  // namespace media
 
 bool AVFoundationGlue::IsAVFoundationSupported() {
+  if (!base::mac::IsOSLionOrLater())
+    return false;
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("AVFoundationMacVideoCapture");
   const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
-  return cmd_line->HasSwitch(switches::kEnableAVFoundation) &&
-      base::mac::IsOSLionOrLater() && [AVFoundationBundle() load];
+  return (cmd_line->HasSwitch(switches::kEnableAVFoundation) ||
+      group_name == "Enabled") && [AVFoundationBundle() load];
 }
 
 NSBundle const* AVFoundationGlue::AVFoundationBundle() {
   return g_avfoundation_handle.Get().bundle();
 }
 
 void* AVFoundationGlue::AVFoundationLibraryHandle() {
   return g_avfoundation_handle.Get().library_handle();
 }
 
@@ skipping 80 matching lines @@
 @implementation AVCaptureDeviceInputGlue
 
 + (CrAVCaptureDeviceInput*)deviceInputWithDevice:(CrAVCaptureDevice*)device
                                            error:(NSError**)outError {
   return [[AVFoundationGlue::AVFoundationBundle()
       classNamed:@"AVCaptureDeviceInput"] deviceInputWithDevice:device
                                                           error:outError];
 }
 
 @end  // @implementation AVCaptureDeviceInputGlue