Merge "Make BluetoothGattCallback.onServiceChanged public" am: 802503736d am: 531993dca1 am: 23c923d197

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1439193

Change-Id: Ie2a9777fbc9a4c5861e07748dfb7596bc547c931