[Win]update overlay swap chain size for power saving on battery mode

1. On battery-power mode, set swap chain size to the source content size
when the swap chain presents upscaled overlay, which is more power
saving (about 1% power saving on Alder Lake and 1.5% power saving on
Raptor Lake with resolution 1280X720 upscaled to 1920x1080) as the video
processor can do the minimal amount of work and the overlay has to read
the minimal amount of data.

2. For letterboxing feature, Optimize the calculation of dest_size/target_rect, and horizontal/vertical shifting.

Bug: 1245835

Change-Id: I9163df7911f046164ca5ff31ee50afe307f58b41
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4691281
Reviewed-by: Chunbo Hua <chunbo.hua@intel.com>
Reviewed-by: Maggie Chen <magchen@chromium.org>
Commit-Queue: Yingying Ma <yingying.ma@intel.com>
Cr-Commit-Position: refs/heads/main@{#1238942}