Add ability to retrieve capabilities for audio input devices to MediaDevicesDispatcherHost.

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 f0c514107dd3fa93d4e6e0d8874f1b13f350ac68..103ec7a388dbb130e203be0144cd08a285f62d4f 100644
--- a/content/renderer/media/user_media_client_impl_unittest.cc
+++ b/content/renderer/media/user_media_client_impl_unittest.cc
@@ -159,6 +159,11 @@ class MockMediaDevicesDispatcherHost
     std::move(client_callback).Run(std::move(result));
   }
 
+  void GetAudioInputCapabilities(
+      GetAudioInputCapabilitiesCallback client_callback) override {
+    NOTREACHED();
+  }
+
   MOCK_METHOD2(SubscribeDeviceChangeNotifications,
                void(MediaDeviceType type, uint32_t subscription_id));
   MOCK_METHOD2(UnsubscribeDeviceChangeNotifications,