Fix getUserMedia so that failure is reported for invalid audio sources.

content/renderer/media/user_media_client_impl_unittest.cc

Index: content/renderer/media/user_media_client_impl_unittest.cc
diff --git a/content/renderer/media/user_media_client_impl_unittest.cc b/content/renderer/media/user_media_client_impl_unittest.cc
index 41f634f55f12dfe6a793f9d8ce59a85e0fae6600..77214b3bb20394160c9d52bb4523f6e6e8f8bef6 100644
--- a/content/renderer/media/user_media_client_impl_unittest.cc
+++ b/content/renderer/media/user_media_client_impl_unittest.cc
@@ -206,9 +206,16 @@ class UserMediaClientImplUnderTest : public UserMediaClientImpl {
     create_source_that_fails_ = should_fail;
   }
 
+  static void SignalSourceReady(
+      const MediaStreamSource::ConstraintsCallback& source_ready,
+      MediaStreamSource* source) {
+    source_ready.Run(source, MEDIA_DEVICE_OK, "");
+  }
+
   MediaStreamAudioSource* CreateAudioSource(
       const StreamDeviceInfo& device,
-      const blink::WebMediaConstraints& constraints) override {
+      const blink::WebMediaConstraints& constraints,
+      const MediaStreamSource::ConstraintsCallback& source_ready) override {
     MediaStreamAudioSource* source;
     if (create_source_that_fails_) {
       class FailedAtLifeAudioSource : public MediaStreamAudioSource {
@@ -225,6 +232,15 @@ class UserMediaClientImplUnderTest : public UserMediaClientImpl {
       source = new MediaStreamAudioSource(true);
     }
     source->SetDeviceInfo(device);
+
+    if (!create_source_that_fails_) {
+      // RunUntilIdle is required for this task to complete.
+      base::ThreadTaskRunnerHandle::Get()->PostTask(
+          FROM_HERE,
+          base::Bind(&UserMediaClientImplUnderTest::SignalSourceReady,
+                     source_ready, source));
+    }
+
     return source;
   }
 
@@ -346,6 +362,7 @@ class UserMediaClientImplTest : public ::testing::Test {
         ms_dispatcher_->audio_input_request_id(),
         ms_dispatcher_->stream_label(), ms_dispatcher_->audio_input_array(),
         ms_dispatcher_->video_array());
+    base::RunLoop().RunUntilIdle();
   }
 
   void StartMockedVideoSource() {