Steps to reproduce:
1. Download attached project
2. Turn on Deep Profiling in the Profiler
3. Enter play mode
4. Pause the game and disable Profile recording after a few seconds
5. Observe that any given frame has a block called "get_copyStdMaterial" in "PostProcessLayer.BuildCommandBuffers"

Results: "PostProcessLayer.BuildCommandBuffers" is called when a material is created which shouldn't happen every frame when using Post-Processing layer's

Reproduced with: 2020.1.0a3, 2019.3.0b2, 2019.2.4f1, 2018.4.9f1

Tested and reproduced with Post Processing Package: 2.0.9, 2.1.7

Note:
- Not reproducible when using Post-Processing which is integrating into Universal RP and HDRP