Default enable content type rtp header extension

BUG=webrtc:7420

Review-Url: https://codereview.webrtc.org/2998843002
Cr-Commit-Position: refs/heads/master@{#19346}
diff --git a/webrtc/media/engine/webrtcvideoengine.cc b/webrtc/media/engine/webrtcvideoengine.cc
index 6813ada..52db773 100644
--- a/webrtc/media/engine/webrtcvideoengine.cc
+++ b/webrtc/media/engine/webrtcvideoengine.cc
@@ -55,13 +55,6 @@
   return webrtc::field_trial::IsEnabled("WebRTC-FlexFEC-03-Advertised");
 }
 
-// If this field trial is enabled, we will report VideoContentType RTP extension
-// in capabilities (thus, it will end up in the default SDP and extension will
-// be sent for all key-frames).
-bool IsVideoContentTypeExtensionFieldTrialEnabled() {
-  return webrtc::field_trial::IsEnabled("WebRTC-VideoContentTypeExtension");
-}
-
 // An encoder factory that wraps Create requests for simulcastable codec types
 // with a webrtc::SimulcastEncoderAdapter. Non simulcastable codec type
 // requests are just passed through to the contained encoder factory.
@@ -430,11 +423,9 @@
   capabilities.header_extensions.push_back(
       webrtc::RtpExtension(webrtc::RtpExtension::kPlayoutDelayUri,
                            webrtc::RtpExtension::kPlayoutDelayDefaultId));
-  if (IsVideoContentTypeExtensionFieldTrialEnabled()) {
-    capabilities.header_extensions.push_back(
-        webrtc::RtpExtension(webrtc::RtpExtension::kVideoContentTypeUri,
-                             webrtc::RtpExtension::kVideoContentTypeDefaultId));
-  }
+  capabilities.header_extensions.push_back(
+      webrtc::RtpExtension(webrtc::RtpExtension::kVideoContentTypeUri,
+                           webrtc::RtpExtension::kVideoContentTypeDefaultId));
   // TODO(ilnik): Add kVideoTimingUri/kVideoTimingDefaultId to capabilities.
   // Possibly inside field trial.
   return capabilities;
diff --git a/webrtc/media/engine/webrtcvideoengine_unittest.cc b/webrtc/media/engine/webrtcvideoengine_unittest.cc
index f31ac51..3af7ef4 100644
--- a/webrtc/media/engine/webrtcvideoengine_unittest.cc
+++ b/webrtc/media/engine/webrtcvideoengine_unittest.cc
@@ -273,29 +273,6 @@
   EXPECT_TRUE(capturer.apply_rotation());
 }
 
-
-// TODO(ilnik): Remove this test once field trial is gone.
-TEST_F(WebRtcVideoEngineTest, SupportsVideoContentTypeHeaderExtension) {
-  // Extension shound not be reported outside of the field trial.
-  RtpCapabilities capabilities = engine_.GetCapabilities();
-  EXPECT_FALSE(capabilities.header_extensions.empty());
-  for (const RtpExtension& extension : capabilities.header_extensions) {
-    EXPECT_NE(extension.uri, RtpExtension::kVideoContentTypeUri);
-  }
-  webrtc::test::ScopedFieldTrials override_field_trials_(
-        "WebRTC-VideoContentTypeExtension/Enabled/");
-  // Should be reported within field trial.
-  capabilities = engine_.GetCapabilities();
-  EXPECT_FALSE(capabilities.header_extensions.empty());
-  for (const RtpExtension& extension : capabilities.header_extensions) {
-    if (extension.uri == RtpExtension::kVideoContentTypeUri) {
-      EXPECT_EQ(RtpExtension::kVideoContentTypeDefaultId, extension.id);
-      return;
-    }
-  }
-  FAIL() << "Video Content Type extension not in header-extension list.";
-}
-
 TEST_F(WebRtcVideoEngineTest, CVOSetHeaderExtensionBeforeAddSendStream) {
   // Allocate the capturer first to prevent early destruction before channel's
   // dtor is called.