Turn some if statements into switch/case.

3/4 to split the the Recents functionality from the rest of
DefaultMixedHandler logic.

Bug: 314971702
Flag: NA
Test: https://android-build.corp.google.com/builds/abtd/run/L13400030000862940
Change-Id: I97f79eec8c6b96607d4bb3fb8ca6548e09524591