Declare `ConversionResult` in `android` namespace am: 19418e32ed

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/2482955

Change-Id: Iccb7f2891542045a6fa772335def6a260d11e4b7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>