Introduce struct MediaConfig, with construction-time settings.

talk/app/webrtc/peerconnectioninterface_unittest.cc

 /*
  * libjingle
  * Copyright 2012 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 2337 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]));
 }
 
+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 bool create_media_controller_called_ = false;
+  mutable cricket::MediaConfig create_media_controller_config_;
+};
+
+// This test verifies 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 this unittest.
+TEST(PeerConnection, TestSettingOfMediaConfig) {

[perkj_webrtc, 2016/02/10 10:41:26]

please split into separate tests. 
1. Test constrinats webrtc::MediaConstraintsInterface::kEnableDscp,
2. Test enable_cpu_overuse_detection 
webrtc::MediaConstraintsInterface::kCpuOveruseDetection
3. Test PeerConnectionInterface::RTCConfiguration config
disable_prerenderer_smoothing

[nisse-webrtc, 2016/02/10 13:42:01]

Done.

+  struct OneTest{
+    bool disable_prerenderer_smoothing;
+    rtc::Optional<bool> input_enable_dscp;
+    bool output_enable_dscp;
+    rtc::Optional<bool> input_enable_cpu_overuse_detection;
+    bool output_enable_cpu_overuse_detection;
+  };
+
+  const std::vector<OneTest> tests = {
+    // No disable_prerenderer_smoothing, no constraints
+    { false,
+      rtc::Optional<bool>(), false,
+      rtc::Optional<bool>(), true },
+    // Non-default constraints
+    { true,
+      rtc::Optional<bool>(true), true,
+      rtc::Optional<bool>(false), false },
+    // Explicit constraints implying default settings
+    { false,
+      rtc::Optional<bool>(false), false,
+      rtc::Optional<bool>(true), true },
+  };
+
+  scoped_refptr<PeerConnectionFactoryForTest> pcf(
+      new rtc::RefCountedObject<PeerConnectionFactoryForTest>());
+
+  pcf->Initialize();
+
+  for (auto test : tests) {
+    FakeConstraints constraints;
+    if (test.input_enable_dscp) {
+      constraints.AddOptional(
+          webrtc::MediaConstraintsInterface::kEnableDscp,
+          *test.input_enable_dscp);
+    }
+    if (test.input_enable_cpu_overuse_detection) {
+      constraints.AddOptional(
+          webrtc::MediaConstraintsInterface::kCpuOveruseDetection,
+          *test.input_enable_cpu_overuse_detection);
+    }
+    PeerConnectionInterface::RTCConfiguration config;
+    config.disable_prerenderer_smoothing = test.disable_prerenderer_smoothing;
+
+    pcf->create_media_controller_called_ = false;
+
+    MockPeerConnectionObserver observer;
+    scoped_refptr<PeerConnectionInterface> pc =
+        pcf->CreatePeerConnection(config, &constraints,
+                                  nullptr, nullptr, &observer);
+    EXPECT_TRUE(pc.get() != nullptr);
+    EXPECT_TRUE(pcf->create_media_controller_called_);
+    EXPECT_EQ(
+        test.disable_prerenderer_smoothing,
+        pcf->create_media_controller_config_.disable_prerenderer_smoothing);
+    EXPECT_EQ(
+        test.output_enable_dscp,
+        pcf->create_media_controller_config_.enable_dscp);
+    EXPECT_EQ(
+        test.output_enable_cpu_overuse_detection,
+        pcf->create_media_controller_config_.enable_cpu_overuse_detection);
+  }
+}
+
 // 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());
 }