Rename stereo video codec to multiplex

This CL only does the rename from"stereo" to multiplex". With this we have a
better name that doesn't clash with audio's usage of stereo.

Bug: webrtc:7671
Change-Id: Iebc3fc20839025f1bc8bcf0e16141bf9744ef652
Reviewed-on: https://webrtc-review.googlesource.com/43242
Commit-Queue: Emircan Uysaler <emircan@webrtc.org>
Reviewed-by: Niklas Enbom <niklas.enbom@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21769}

media/engine/multiplexcodecfactory_unittest.cc

@@ -0,0 +1,47 @@
+/*
+ *  Copyright (c) 2017 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.
+ */
+
+#include "media/engine/multiplexcodecfactory.h"
+
+#include <utility>
+
+#include "api/video_codecs/sdp_video_format.h"
+#include "api/video_codecs/video_decoder.h"
+#include "api/video_codecs/video_encoder.h"
+#include "media/base/mediaconstants.h"
+#include "media/engine/internaldecoderfactory.h"
+#include "media/engine/internalencoderfactory.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+
+TEST(MultiplexDecoderFactory, CreateVideoDecoder) {
+  std::unique_ptr<VideoDecoderFactory> internal_factory(
+      new InternalDecoderFactory());
+  MultiplexDecoderFactory factory(std::move(internal_factory));
+  std::unique_ptr<VideoDecoder> decoder =
+      factory.CreateVideoDecoder(SdpVideoFormat(
+          cricket::kMultiplexCodecName,
+          {{cricket::kCodecParamAssociatedCodecName, cricket::kVp9CodecName}}));
+  EXPECT_TRUE(decoder);
+}
+
+TEST(MultiplexEncoderFactory, CreateVideoEncoder) {
+  std::unique_ptr<VideoEncoderFactory> internal_factory(
+      new InternalEncoderFactory());
+  MultiplexEncoderFactory factory(std::move(internal_factory));
+  std::unique_ptr<VideoEncoder> encoder =
+      factory.CreateVideoEncoder(SdpVideoFormat(
+          cricket::kMultiplexCodecName,
+          {{cricket::kCodecParamAssociatedCodecName, cricket::kVp9CodecName}}));
+  EXPECT_TRUE(encoder);
+}
+
+}  // namespace webrtc