Resets mojo typed members before binding new pipes.

Before this fix, we were unable to successfully restart the
Media Perception Service and re-connect over Mojo IPC.

Bug: 1129628
Test: Verified on-device this fixes the bug.
Change-Id: I3eb60d99320c41ff2aef357ed9ae83a18d9d715a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2422183Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Luke Sorenson <lasoren@chromium.org>
Commit-Queue: Luke Sorenson <lasoren@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808956}

extensions/browser/api/media_perception_private/media_perception_api_manager.cc

@@ -413,6 +413,7 @@ void MediaPerceptionAPIManager::SendMojoInvitation(
                                  base::kNullProcessHandle,
                                  channel.TakeLocalEndpoint());
 
+  media_perception_service_.reset();
   media_perception_service_.Bind(
       mojo::PendingRemote<
           chromeos::media_perception::mojom::MediaPerceptionService>(
@@ -468,6 +469,7 @@ void MediaPerceptionAPIManager::OnBootstrapMojoConnection(
     return;
   }
 
+  media_perception_controller_.reset();
   auto controller_receiver =
       media_perception_controller_.BindNewPipeAndPassReceiver();