Merge "Log UiEvents useful for calculating dream overlay start latency." into tm-dev am: 3ecf7b2c am: 2a64c70f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17227584

Change-Id: I6b92725cc6e829c5d4a0b6c552f699b793c73222