DesktopCaptureDevice is available when webrtc is enabled.

content/browser/renderer_host/media/video_capture_manager.cc

 // Copyright (c) 2012 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.
 
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 643 matching lines @@
 
 std::unique_ptr<media::VideoCaptureDevice>
 VideoCaptureManager::DoStartTabCaptureOnDeviceThread(
     const std::string& id,
     const media::VideoCaptureParams& params,
     std::unique_ptr<VideoCaptureDevice::Client> device_client) {
   SCOPED_UMA_HISTOGRAM_TIMER("Media.VideoCaptureManager.StartDeviceTime");
   DCHECK(IsOnDeviceThread());
 
   std::unique_ptr<VideoCaptureDevice> video_capture_device;
+#if defined(ENABLE_SCREEN_CAPTURE)
 #if defined(OS_LINUX) || defined(OS_MACOSX) || defined(OS_WIN)

[boliu, 2017/01/10 17:31:51]

don't need the inner define anymore

[byungchul, 2017/01/10 17:40:38]

Done.

   video_capture_device = WebContentsVideoCaptureDevice::Create(id);
 #endif
+#endif
 
   if (!video_capture_device) {
     device_client->OnError(FROM_HERE, "Could not create capture device");
     return nullptr;
   }
 
   video_capture_device->AllocateAndStart(params, std::move(device_client));
   return video_capture_device;
 }
 
@@ skipping 644 matching lines @@
     if (!device_in_queue) {
       // Session ID is only valid for Screen capture. So we can fake it to
       // resume video capture devices here.
       QueueStartDevice(kFakeSessionId, entry.get(), entry->parameters);
     }
   }
 }
 #endif  // defined(OS_ANDROID)
 
 }  // namespace content