ui: Cleanup class/struct forward declarations

services/video_capture/device_mock_to_media_adapter.cc

Index: services/video_capture/device_mock_to_media_adapter.cc
diff --git a/services/video_capture/device_mock_to_media_adapter.cc b/services/video_capture/device_mock_to_media_adapter.cc
index bd3ea0877669ad7aa657bf1263e67c659f781af3..ad6cb5a502fe57e99593091472458671e912b668 100644
--- a/services/video_capture/device_mock_to_media_adapter.cc
+++ b/services/video_capture/device_mock_to_media_adapter.cc
@@ -9,8 +9,8 @@
 namespace video_capture {
 
 DeviceMockToMediaAdapter::DeviceMockToMediaAdapter(
-    mojom::MockVideoCaptureDevicePtr device)
-    : device_(std::move(device)) {}
+    mojom::MockVideoCaptureDevicePtr* device)
+    : device_(device) {}
 
 DeviceMockToMediaAdapter::~DeviceMockToMediaAdapter() = default;
 
@@ -24,13 +24,13 @@ void DeviceMockToMediaAdapter::AllocateAndStart(
       base::MakeUnique<DeviceClientMediaToMojoAdapter>(std::move(client)),
       std::move(client_request));
 
-  device_->AllocateAndStart(std::move(client_proxy));
+  (*device_)->AllocateAndStart(std::move(client_proxy));
 }
 
 void DeviceMockToMediaAdapter::RequestRefreshFrame() {}
 
 void DeviceMockToMediaAdapter::StopAndDeAllocate() {
-  device_->StopAndDeAllocate();
+  (*device_)->StopAndDeAllocate();
 }
 
 void DeviceMockToMediaAdapter::GetPhotoCapabilities(