Don't cache video codec list in VideoEngine2.

webrtc/media/engine/webrtcvideoengine2_unittest.cc

Index: webrtc/media/engine/webrtcvideoengine2_unittest.cc
diff --git a/webrtc/media/engine/webrtcvideoengine2_unittest.cc b/webrtc/media/engine/webrtcvideoengine2_unittest.cc
index c473a4099f98d9838a0a9de28857997253f87141..14703ac4bb52e7c994e409fee23f7303ef35009f 100644
--- a/webrtc/media/engine/webrtcvideoengine2_unittest.cc
+++ b/webrtc/media/engine/webrtcvideoengine2_unittest.cc
@@ -12,6 +12,7 @@
 #include <list>
 #include <map>
 #include <memory>
+#include <unordered_set>
 #include <vector>
 
 #include "webrtc/base/arraysize.h"
@@ -26,6 +27,8 @@
 #include "webrtc/media/engine/simulcast.h"
 #include "webrtc/media/engine/webrtcvideoengine2.h"
 #include "webrtc/media/engine/webrtcvoiceengine.h"
+#include "webrtc/modules/video_coding/codecs/h264/include/h264.h"
+#include "webrtc/modules/video_coding/codecs/vp9/include/vp9.h"
 #include "webrtc/test/field_trial.h"
 #include "webrtc/video_encoder.h"
 
@@ -100,6 +103,14 @@ void VerifySendStreamHasRtxTypes(const webrtc::VideoSendStream::Config& config,
                 it->second == config.rtp.ulpfec.red_rtx_payload_type);
   }
 }
+
+std::unordered_set<std::string> GetCodecNames(
+    const cricket::WebRtcVideoEngine2& engine) {
+  std::unordered_set<std::string> codec_names;
+  for (const auto& codec : engine.codecs())
+    codec_names.insert(codec.name);
+  return codec_names;
+}
 }  // namespace
 
 namespace cricket {
@@ -749,6 +760,42 @@ TEST_F(WebRtcVideoEngine2Test, SimulcastDisabledForH264) {
   EXPECT_TRUE(channel->SetVideoSend(ssrcs[0], true, nullptr, nullptr));
 }
 
+// Test that internal codecs are added to the codec list.
+// Update this test if the internal codecs are changed!
+TEST_F(WebRtcVideoEngine2Test, ReportSupportedInternalCodecs) {

[perkj_webrtc, 2016/11/28 09:20:06]

The fix is for  different codecs when the engine has been reset right? 
So can we write a test that Gets the codecs and then reinitialise the engine
with the  experiment set and reinitialise the engine and get the codecs again.

[brandtr, 2016/11/28 10:40:15]

Done. I did not reinitialize the engine in the test however, as the field trial
change is effective without reinitializing the engine.

+  engine_.Init();
+  std::unordered_set<std::string> codec_names = GetCodecNames(engine_);
+
+  size_t expected_num_codecs = 4;
+  EXPECT_NE(codec_names.find("VP8"), codec_names.end());

[magjed_webrtc, 2016/11/28 10:31:31]

nit: I think it would be slightly cleaner to write it like:
EXPECT_EQ(1u, codec_names.count("VP8"));

[brandtr, 2016/11/28 10:47:40]

Agree. I'm used to the find()/end() style after working with std::set's, but
since this is a hash table, count() is nicer.

+  if (webrtc::VP9Encoder::IsSupported()) {
+    EXPECT_NE(codec_names.find("VP9"), codec_names.end());
+    ++expected_num_codecs;
+  }
+  if (webrtc::H264Encoder::IsSupported()) {
+    EXPECT_NE(codec_names.find("H264"), codec_names.end());
+    ++expected_num_codecs;
+  }
+  EXPECT_NE(codec_names.find("rtx"), codec_names.end());
+  EXPECT_NE(codec_names.find("red"), codec_names.end());
+  EXPECT_NE(codec_names.find("ulpfec"), codec_names.end());
+  EXPECT_EQ(expected_num_codecs, codec_names.size());
+}
+
+class WebRtcVideoEngine2FlexfecTest : public WebRtcVideoEngine2Test {
+ public:
+  WebRtcVideoEngine2FlexfecTest()
+      : WebRtcVideoEngine2Test("WebRTC-FlexFEC-03/Enabled/") {}
+};
+
+// TODO(brandtr): Merge with test above, when the FlexFEC field trial is gone.
+TEST_F(WebRtcVideoEngine2FlexfecTest, ReportSupportedInternalCodecs) {
+  engine_.Init();
+  std::unordered_set<std::string> codec_names = GetCodecNames(engine_);
+
+  EXPECT_NE(codec_names.find("flexfec-03"), codec_names.end());
+}
+
 // Test that external codecs are added to the end of the supported codec list.
 TEST_F(WebRtcVideoEngine2Test, ReportSupportedExternalCodecs) {
   cricket::FakeWebRtcVideoEncoderFactory encoder_factory;
@@ -761,7 +808,7 @@ TEST_F(WebRtcVideoEngine2Test, ReportSupportedExternalCodecs) {
   cricket::VideoCodec internal_codec = codecs.front();
   cricket::VideoCodec external_codec = codecs.back();
 
-  // The external codec will appear at last.
+  // The external codec will appear last in the vector.
   EXPECT_EQ("VP8", internal_codec.name);
   EXPECT_EQ("FakeExternalCodec", external_codec.name);
 }