Plumb owner pid into Layer

For shared timeline visualization, the pid of the process owning the
layer is needed to show the information in the respective process
tracks. This change stores the newly added METADATA_OWNER_PID
information sent as a part of the Layer creation args

Bug: 170911969
Test: pid section of `adb shell dumpsys SurfaceFlinger --frametimeline -<all/jank>`

Change-Id: Ib1cd9b6239501b0b92283dca19d7de3916fff604