Introduce struct MediaConfig, with construction-time settings.

webrtc/api/peerconnectioninterface_unittest.cc

 /*
  *  Copyright 2012 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.
  */
 
@@ skipping 2310 matching lines @@
       webrtc::CreateSessionDescription(SessionDescriptionInterface::kOffer, sdp,
                                        nullptr));
 
   EXPECT_TRUE(DoSetLocalDescription(updated_desc.release()));
   senders = pc_->GetSenders();
   EXPECT_EQ(2u, senders.size());
   EXPECT_TRUE(ContainsSender(senders, kAudioTracks[0]));
   EXPECT_TRUE(ContainsSender(senders, kVideoTracks[0]));
 }
 
+// The PeerConnectionMediaConfig tests below verify that configuration
+// and constraints are propagated into the MediaConfig passed to
+// CreateMediaController. These settings are intended for MediaChannel
+// constructors, but that is not exercised by these unittest.
+class PeerConnectionFactoryForTest : public webrtc::PeerConnectionFactory {
+ public:
+  webrtc::MediaControllerInterface* CreateMediaController(
+      const cricket::MediaConfig& config) const override {
+    create_media_controller_called_ = true;
+    create_media_controller_config_ = config;
+
+    webrtc::MediaControllerInterface* mc =
+        PeerConnectionFactory::CreateMediaController(config);
+    EXPECT_TRUE(mc != nullptr);
+    return mc;
+  }
+
+  // Mutable, so they can be modified in the above const-declared method.
+  mutable bool create_media_controller_called_ = false;
+  mutable cricket::MediaConfig create_media_controller_config_;
+};
+
+// This test verifies the DSCP constraint is recognized and passed to
+// the CreateMediaController.
+TEST(PeerConnectionMediaConfig, TestDscpConstraint) {
+  scoped_refptr<PeerConnectionFactoryForTest> pcf(
+      new rtc::RefCountedObject<PeerConnectionFactoryForTest>());
+  pcf->Initialize();
+
+  EXPECT_FALSE(pcf->create_media_controller_config_.enable_dscp);
+
+  // Without constraint, default value is false

[perkj_webrtc, 2016/02/11 12:32:08]

nit add . Write complete sentences.

[nisse-webrtc, 2016/02/11 13:45:08]

Done.

+  scoped_refptr<PeerConnectionInterface> pc;

[perkj_webrtc, 2016/02/11 12:32:07]

nit: move to where it is used. ie 
scoped_refptr<PeerConnectionInterface> pc( pcf->.....

here and below.

[nisse-webrtc, 2016/02/11 13:45:08]

I did it this way because I wanted both calls 
pc = pcf->CreatePeerConnection to have the same form.

Anyway, this will likely be moot when I rewrite the tests per your other
comment.

+  PeerConnectionInterface::RTCConfiguration config;
+  FakeConstraints constraints;
+  MockPeerConnectionObserver observer;
+
+  pc = pcf->CreatePeerConnection(config, &constraints, nullptr, nullptr,
+                                 &observer);
+  ASSERT_TRUE(pc.get() != nullptr);
+  EXPECT_TRUE(pcf->create_media_controller_called_);
+  EXPECT_FALSE(pcf->create_media_controller_config_.enable_dscp);
+
+  // With constraint set to true
+  pcf->create_media_controller_called_ = false;
+
+  constraints.AddOptional(webrtc::MediaConstraintsInterface::kEnableDscp, true);
+
+  pc = pcf->CreatePeerConnection(config, &constraints, nullptr, nullptr,
+                                 &observer);
+  EXPECT_TRUE(pc.get() != nullptr);

[perkj_webrtc, 2016/02/11 12:32:08]

ASSERT_TRUE

[nisse-webrtc, 2016/02/11 13:45:08]

Done.

+  EXPECT_TRUE(pcf->create_media_controller_called_);
+  EXPECT_TRUE(pcf->create_media_controller_config_.enable_dscp);
+}
+
+// This test verifies the cpu overuse detection constraint is
+// recognized and passed to the CreateMediaController.
+TEST(PeerConnectionMediaConfig, TestCpuOveruseConstraint) {
+  scoped_refptr<PeerConnectionFactoryForTest> pcf(
+      new rtc::RefCountedObject<PeerConnectionFactoryForTest>());
+  pcf->Initialize();
+
+  EXPECT_FALSE(pcf->create_media_controller_config_.enable_dscp);
+
+  // Without constraint, default value is true
+  PeerConnectionInterface::RTCConfiguration config;
+  FakeConstraints constraints;
+  MockPeerConnectionObserver observer;
+  scoped_refptr<PeerConnectionInterface> pc;
+
+  pc = pcf->CreatePeerConnection(config, &constraints, nullptr, nullptr,
+                                 &observer);
+  ASSERT_TRUE(pc.get() != nullptr);
+  EXPECT_TRUE(pcf->create_media_controller_called_);
+  EXPECT_TRUE(
+      pcf->create_media_controller_config_.enable_cpu_overuse_detection);
+
+  // With constraint set to false
+  pcf->create_media_controller_called_ = false;
+
+  constraints.AddOptional(
+      webrtc::MediaConstraintsInterface::kCpuOveruseDetection, false);
+
+  pc = pcf->CreatePeerConnection(config, &constraints, nullptr, nullptr,
+                                 &observer);
+  ASSERT_TRUE(pc.get() != nullptr);
+  EXPECT_TRUE(pcf->create_media_controller_called_);
+  EXPECT_FALSE(
+      pcf->create_media_controller_config_.enable_cpu_overuse_detection);
+}
+
+// This test verifies the disable_prerenderer_smoothing flag is
+// propagated from RTCConfiguration to the CreateMediaController call.
+TEST(PeerConnectionMediaConfig, TestDisablePrerenderFlag) {
+  scoped_refptr<PeerConnectionFactoryForTest> pcf(
+      new rtc::RefCountedObject<PeerConnectionFactoryForTest>());
+  pcf->Initialize();
+
+  EXPECT_FALSE(pcf->create_media_controller_config_.enable_dscp);
+
+  // Default value, false
+  PeerConnectionInterface::RTCConfiguration config;
+  FakeConstraints constraints;
+  MockPeerConnectionObserver observer;
+  scoped_refptr<PeerConnectionInterface> pc;
+
+  pc = pcf->CreatePeerConnection(config, &constraints, nullptr, nullptr,
+                                 &observer);
+  ASSERT_TRUE(pc.get() != nullptr);
+  EXPECT_TRUE(pcf->create_media_controller_called_);
+  EXPECT_FALSE(
+      pcf->create_media_controller_config_.disable_prerenderer_smoothing);
+
+  // Flag set
+  pcf->create_media_controller_called_ = false;

[perkj_webrtc, 2016/02/11 12:32:07]

right - this should actually be 6 tests instead to avoid this.

I would use TEST_F with a test fixture to setup the test. Then create a method
where I provide a RTCConfiguration and put in the constraints. Then only check
the expectations in each test. 

[nisse-webrtc, 2016/02/11 13:45:08]

I'll do. I guess we'll need a few iterations more...

+
+  config.disable_prerenderer_smoothing = true;
+  pc = pcf->CreatePeerConnection(config, &constraints, nullptr, nullptr,
+                                 &observer);
+  EXPECT_TRUE(pc.get() != nullptr);
+  EXPECT_TRUE(pcf->create_media_controller_called_);
+  EXPECT_TRUE(
+      pcf->create_media_controller_config_.disable_prerenderer_smoothing);
+}
+
 // The following tests verify that session options are created correctly.
 // TODO(deadbeef): Convert these tests to be more end-to-end. Instead of
 // "verify options are converted correctly", should be "pass options into
 // CreateOffer and verify the correct offer is produced."
 
 TEST(CreateSessionOptionsTest, GetOptionsForOfferWithInvalidAudioOption) {
   RTCOfferAnswerOptions rtc_options;
   rtc_options.offer_to_receive_audio = RTCOfferAnswerOptions::kUndefined - 1;
 
   cricket::MediaSessionOptions options;
@@ skipping 148 matching lines @@
   FakeConstraints updated_answer_c;
   answer_c.SetMandatoryReceiveAudio(false);
   answer_c.SetMandatoryReceiveVideo(false);
 
   cricket::MediaSessionOptions updated_answer_options;
   EXPECT_TRUE(
       ParseConstraintsForAnswer(&updated_answer_c, &updated_answer_options));
   EXPECT_TRUE(updated_answer_options.has_audio());
   EXPECT_TRUE(updated_answer_options.has_video());
 }