DesktopCaptureDevice is available when webrtc is enabled.

content/browser/BUILD.gn

 # Copyright 2014 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("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
 import("//printing/features/features.gni")
 import("//third_party/WebKit/public/public_features.gni")
@@ skipping 1493 matching lines @@
     if (is_linux || is_mac || is_win) {
       sources += [
         "media/capture/desktop_capture_device.cc",
         "media/capture/desktop_capture_device.h",
       ]
       deps += [ "//third_party/webrtc/modules/desktop_capture" ]
     }
   }
 
   # Desktop screen capture implementations that are not dependent on WebRTC.
-  if (is_linux || is_mac || is_win) {
+  if ((is_linux && !(is_chromecast && is_cast_audio_only)) || is_mac || is_win) {

[halliwell, 2017/01/10 17:45:44]

From the CL description, it sounds like any linux build with use_aura = 0 could
have this problem.  Did I understand that right?  If so, would it be better to
generalise this to (is_linux && use_aura) ?

(I'm always wary of sprinkling is_chromecast too wide)

     defines += [ "ENABLE_SCREEN_CAPTURE=1" ]
     sources += [
       "media/capture/cursor_renderer.cc",
       "media/capture/cursor_renderer.h",
       "media/capture/web_contents_video_capture_device.cc",
       "media/capture/web_contents_video_capture_device.h",
       "media/capture/window_activity_tracker.cc",
       "media/capture/window_activity_tracker.h",
     ]
     if (use_aura) {
@@ skipping 481 matching lines @@
   if (!is_component_build) {
     public_deps = [
       ":browser",
     ]
   } else {
     public_deps = [
       "//third_party/leveldatabase",
     ]
   }
 }