Adds unit test for ADM on Linux

webrtc/modules/audio_device/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("../../webrtc.gni")
 
@@ skipping 257 matching lines @@
     ]
     deps = [
       ":audio_device",
       ":mock_audio_device",
       "../../base:rtc_base_approved",
       "../../system_wrappers:system_wrappers",
       "../../test:test_support",
       "../utility:utility",
       "//testing/gmock",
     ]
+    if (is_linux) {
+      sources += [ "audio_device_unittest.cc" ]
+    }
     if (is_android) {
       # Need to disable error due to the line in
       # base/android/jni_android.h triggering it:
       # const BASE_EXPORT jobject GetApplicationContext()
       # error: type qualifiers ignored on function return type
       cflags = [ "-Wno-ignored-qualifiers" ]
       sources += [
         "android/audio_device_unittest.cc",
         "android/audio_manager_unittest.cc",
         "android/ensure_initialized.cc",
@@ skipping 63 matching lines @@
       "android/java/src/org/webrtc/voiceengine/WebRtcAudioManager.java",
       "android/java/src/org/webrtc/voiceengine/WebRtcAudioRecord.java",
       "android/java/src/org/webrtc/voiceengine/WebRtcAudioTrack.java",
       "android/java/src/org/webrtc/voiceengine/WebRtcAudioUtils.java",
     ]
     deps = [
       "//webrtc/base:base_java",
     ]
   }
 }