Adding placeholder for low bandwidth audio test

This will allow the trybots to be updated to start running this new test
executable, so that they can be used when landing this CL which will
replace the dummy test with real code:
https://codereview.webrtc.org/2694203002

Most likely, the trybots will just run the test binary while the perf bots
will run a Python wrapper script that takes care of the post-processing
to calculate audio quality using PESQ.

BUG=webrtc:7229
NOTRY=True

Review-Url: https://codereview.webrtc.org/2717683002
Cr-Commit-Position: refs/heads/master@{#17063}
diff --git a/webrtc/audio/BUILD.gn b/webrtc/audio/BUILD.gn
index acd8dfa..a6a22e6 100644
--- a/webrtc/audio/BUILD.gn
+++ b/webrtc/audio/BUILD.gn
@@ -7,6 +7,10 @@
 # be found in the AUTHORS file in the root of the source tree.
 
 import("../webrtc.gni")
+if (is_android) {
+  import("//build/config/android/config.gni")
+  import("//build/config/android/rules.gni")
+}
 
 rtc_static_library("audio") {
   sources = [
@@ -79,4 +83,20 @@
       suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
     }
   }
+
+  if (rtc_enable_protobuf) {
+    rtc_executable("low_bandwidth_audio_test") {
+      testonly = true
+
+      sources = [
+        "test/low_bandwidth_audio_test.cc",
+      ]
+
+      deps = []
+
+      if (is_android) {
+        deps += [ "//testing/android/native_test:native_test_support" ]
+      }
+    }
+  }
 }