Remove device enumeration, caching and monitoring from MediaStreamManager.

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 5143fceecb8515804021492424dc231f5e5e5723..24214c266a6fb2e50be3c883e189a139978ffcb3 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -1148,6 +1148,7 @@ test("content_unittests") {
     "../browser/renderer_host/media/audio_input_sync_writer_unittest.cc",
     "../browser/renderer_host/media/audio_output_device_enumerator_unittest.cc",
     "../browser/renderer_host/media/audio_renderer_host_unittest.cc",
+    "../browser/renderer_host/media/media_devices_manager_unittest.cc",
     "../browser/renderer_host/media/media_stream_dispatcher_host_unittest.cc",
     "../browser/renderer_host/media/media_stream_manager_unittest.cc",
     "../browser/renderer_host/media/media_stream_ui_proxy_unittest.cc",