Allow mocking SendSideCongestionController for Call tests.

webrtc/modules/congestion_controller/BUILD.gn

 # Copyright (c) 2014 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.
 
 import("../../webrtc.gni")
 
@@ skipping 83 matching lines @@
       "../remote_bitrate_estimator:mock_remote_bitrate_observer",
       "../remote_bitrate_estimator:remote_bitrate_estimator",
       "../rtp_rtcp:rtp_rtcp",
       "//testing/gmock",
     ]
     if (!build_with_chromium && is_clang) {
       # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
       suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
     }
   }
+
+  rtc_source_set("mock_send_side_congestion_controller") {
+    testonly = true
+    sources = [
+      "include/mock/mock_send_side_congestion_controller.h",
+    ]
+    deps = [
+      ":congestion_controller",
+      "../../test:test_support",
+    ]
+  }
 }