Reland Move fake_audio_device to its own target.

webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc

Index: webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc
diff --git a/webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc b/webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc
index 2801c65b907bbf0cedb2426f2741dcb9bb9f72a0..5e5d8eea49c04b89f9a13fd96bd62df7597d27f7 100644
--- a/webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc
+++ b/webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc
@@ -70,11 +70,11 @@ class VerifyingAudioReceiver : public NullRtpData {
 
 class RTPCallback : public NullRtpFeedback {
  public:
-  int32_t OnInitializeDecoder(const int8_t payloadType,
+  int32_t OnInitializeDecoder(int8_t payloadType,
                               const char payloadName[RTP_PAYLOAD_NAME_SIZE],
-                              const int frequency,
-                              const size_t channels,
-                              const uint32_t rate) override {
+                              int frequency,
+                              size_t channels,
+                              uint32_t rate) override {
     EXPECT_EQ(0u, rate) << "The rate should be zero";
     return 0;
   }