Add a test that all //api/test headers are compilable.

Bug: webrtc:10376
Change-Id: I2a1ea24ddf5980c76660724fae68c16179bb25a7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/125682
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Yves Gerey <yvesg@google.com>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27119}
diff --git a/api/test/compile_all_headers.cc b/api/test/compile_all_headers.cc
new file mode 100644
index 0000000..47c5c6e
--- /dev/null
+++ b/api/test/compile_all_headers.cc
@@ -0,0 +1,45 @@
+/*
+ *  Copyright 2019 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.
+ */
+
+// This file verifies that all include files in this directory can be
+// compiled without errors or other required includes.
+
+// Note: The following header files are not not tested here, as their
+// associated targets are not included in all configurations.
+// "api/test/audioproc_float.h"
+// "api/test/create_video_quality_test_fixture.h"
+// "api/test/neteq_simulator_factory.h"
+// "api/test/video_quality_test_fixture.h"
+// The following header files are also not tested:
+// "api/test/create_simulcast_test_fixture.h"
+// "api/test/create_videocodec_test_fixture.h"
+// "api/test/neteq_simulator.h"
+// "api/test/simulated_network.h"
+// "api/test/simulcast_test_fixture.h"
+// "api/test/test_dependency_factory.h"
+// "api/test/videocodec_test_fixture.h"
+// "api/test/videocodec_test_stats.h"
+
+#include "api/test/fake_frame_decryptor.h"
+#include "api/test/fake_frame_encryptor.h"
+#include "api/test/fake_media_transport.h"
+#include "api/test/loopback_media_transport.h"
+#include "api/test/mock_audio_mixer.h"
+#include "api/test/mock_frame_decryptor.h"
+#include "api/test/mock_frame_encryptor.h"
+#include "api/test/mock_peerconnectioninterface.h"
+#include "api/test/mock_rtpreceiver.h"
+#include "api/test/mock_rtpsender.h"
+#include "api/test/mock_video_bitrate_allocator.h"
+#include "api/test/mock_video_bitrate_allocator_factory.h"
+#include "api/test/mock_video_decoder.h"
+#include "api/test/mock_video_decoder_factory.h"
+#include "api/test/mock_video_encoder.h"
+#include "api/test/mock_video_encoder_factory.h"