Reland of "Adds a WebRTC browser_test with opus dtx enabled.".

chrome/browser/media/webrtc_browsertest_base.cc

Index: chrome/browser/media/webrtc_browsertest_base.cc
diff --git a/chrome/browser/media/webrtc_browsertest_base.cc b/chrome/browser/media/webrtc_browsertest_base.cc
index 64311b8408a433e95d471f84f7eaa4623cacab2e..4e574ab9b3fd090462a58125f5cd608f73d60be2 100644
--- a/chrome/browser/media/webrtc_browsertest_base.cc
+++ b/chrome/browser/media/webrtc_browsertest_base.cc
@@ -336,15 +336,8 @@ void WebRtcTestBase::SetupPeerconnectionWithCertificateWithoutLocalStream(
 }
 
 std::string WebRtcTestBase::CreateLocalOffer(
-      content::WebContents* from_tab,
-      std::string default_video_codec) const {
-  if (default_video_codec.empty())
-    default_video_codec = "null";
-  else
-    default_video_codec = "'" + default_video_codec + "'";
-  std::string javascript = base::StringPrintf(
-      "createLocalOffer({}, %s)", default_video_codec.c_str());
-  std::string response = ExecuteJavascript(javascript, from_tab);
+    content::WebContents* from_tab) const {
+  std::string response = ExecuteJavascript("createLocalOffer({})", from_tab);
   EXPECT_EQ("ok-", response.substr(0, 3)) << "Failed to create local offer: "
       << response;
 
@@ -352,10 +345,8 @@ std::string WebRtcTestBase::CreateLocalOffer(
   return local_offer;
 }
 
-std::string WebRtcTestBase::CreateAnswer(
-    std::string local_offer,
-    content::WebContents* to_tab,
-    std::string default_video_codec) const {
+std::string WebRtcTestBase::CreateAnswer(std::string local_offer,
+                                         content::WebContents* to_tab) const {
   std::string javascript =
       base::StringPrintf("receiveOfferFromPeer('%s', {})", local_offer.c_str());
   std::string response = ExecuteJavascript(javascript, to_tab);
@@ -364,17 +355,11 @@ std::string WebRtcTestBase::CreateAnswer(
       << response;
 
   std::string answer = response.substr(3);
-
-  if (!default_video_codec.empty()) {
-    response = ExecuteJavascript(
-        base::StringPrintf("verifyDefaultVideoCodec('%s', '%s')",
-                           answer.c_str(), default_video_codec.c_str()),
-        to_tab);
-    EXPECT_EQ("ok-", response.substr(0, 3))
-        << "Receiving peer failed to verify default codec: "
-        << response;
-  }
-
+  response = ExecuteJavascript(
+      base::StringPrintf("verifyDefaultVideoCodec('%s')", answer.c_str()),
+      to_tab);
+  EXPECT_EQ("ok-", response.substr(0, 3))
+      << "Receiving peer failed to verify default codec: " << response;
   return answer;
 }
 
@@ -399,10 +384,9 @@ void WebRtcTestBase::GatherAndSendIceCandidates(
 }
 
 void WebRtcTestBase::NegotiateCall(content::WebContents* from_tab,
-                                   content::WebContents* to_tab,
-                                   const std::string& video_codec) const {
-  std::string local_offer = CreateLocalOffer(from_tab, video_codec);
-  std::string answer = CreateAnswer(local_offer, to_tab, video_codec);
+                                   content::WebContents* to_tab) const {
+  std::string local_offer = CreateLocalOffer(from_tab);
+  std::string answer = CreateAnswer(local_offer, to_tab);
   ReceiveAnswer(answer, from_tab);
 
   // Send all ICE candidates (wait for gathering to finish if necessary).
@@ -481,3 +465,14 @@ void WebRtcTestBase::GenerateAndCloneCertificate(
 void WebRtcTestBase::VerifyStatsGenerated(content::WebContents* tab) const {
   EXPECT_EQ("ok-got-stats", ExecuteJavascript("verifyStatsGenerated()", tab));
 }
+
+void WebRtcTestBase::SetDefaultVideoCodec(
+    content::WebContents* tab,
+    const std::string& video_codec) const {
+  EXPECT_EQ("ok-forced",
+            ExecuteJavascript("forceVideoCodec('" + video_codec + "')", tab));
+}
+
+void WebRtcTestBase::EnableOpusDtx(content::WebContents* tab) const {
+  EXPECT_EQ("ok-forced", ExecuteJavascript("forceOpusDtx()", tab));
+}