Add comment to unit test for renderToAssociatedSink constraint

content/renderer/media/user_media_client_impl_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/user_media_client_impl.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <utility>
@@ skipping 606 matching lines @@
 }
 
 TEST_F(UserMediaClientImplTest, RenderToAssociatedSinkConstraint) {
   // For a null UserMediaRequest (no audio requested), we expect false.
   used_media_impl_->RequestUserMedia();
   EXPECT_FALSE(used_media_impl_->UserMediaRequestHasAutomaticDeviceSelection(
       ms_dispatcher_->audio_input_request_id()));
   used_media_impl_->DeleteRequest(ms_dispatcher_->audio_input_request_id());
 
   // If audio is requested, but no constraint, it should be true.
+  // Currently we expect it to be false due to a suspected bug in the
+  // device-matching code causing issues with some sound adapters.
+  // See crbug.com/604523
   MockConstraintFactory factory;
   blink::WebMediaConstraints audio_constraints =
       factory.CreateWebMediaConstraints();
   EXPECT_FALSE(AudioRequestHasAutomaticDeviceSelection(
       factory.CreateWebMediaConstraints()));
 
   // If the constraint is present, it should dictate the result.
   factory.Reset();
   factory.AddAdvanced().renderToAssociatedSink.setExact(true);
   EXPECT_TRUE(AudioRequestHasAutomaticDeviceSelection(
@@ skipping 41 matching lines @@
   // Now we close the web frame, if in the above Stop() call,
   // UserMediaClientImpl accidentally removed audio track, then video track will
   // be removed again here, which is incorrect.
   used_media_impl_->FrameWillClose();
   blink::WebHeap::collectAllGarbageForTesting();
   EXPECT_EQ(1, ms_dispatcher_->stop_video_device_counter());
   EXPECT_EQ(1, ms_dispatcher_->stop_audio_device_counter());
 }
 
 }  // namespace content