Refactor PaintChunksToCcLayer to prepare for DrawScrollingContentsOp

- The content of SwitchToChunkState() is now directly inlined in
  Convert(), and is moved out of the display item loop because
  crrev.com/c/5118743 will need to check the result of each of the
  switches of transform, clip and effect separately.
- As the original action of SwitchToChunkState() is no longer executed
  lazily in the display item loop, now check whether we need to
  convert a chunk at the beginning of the chunk loop body.

Bug: 40517276
Change-Id: I70cbeda7457d112debc26602c686e64442666dd3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5422663
Reviewed-by: Stefan Zager <szager@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1290263}