In bug 1088118 we will switch to using performance markers from User Timing in order to denote performance events, as opposed to normal events. In order to efficiently measure performance, we need an API available to the System app to capture many performance markers that are contextual to an application. The performance test can then come along and pull all these markers once the test is over.

By interacting with performance entries using logcat, we don't need to introduce a new API to the System app.