A bit more refactoring in BackgroundDexOptService

Extract convenient methods to help with:
- adding a shell command to run the background dexopt job
- extending idleOptimizations to cover secondary dex files

Test: device boots, background job run.
Bug: 32871170
Change-Id: I18fde62a1cb05c030a620722d5f217589beaefb1
1 file changed