Add memory usage metric for OCR and Main Content Extraction services.

Memory usage of OCR and Main Content Extraction services are monitored
and the max usage per process instance is recorded.
Older metrics on memory state before OCR service are removed since the
new metrics better indicate the usage and can be used in future to stop
service initialization when enough memory is not available.

OBSOLETE_HISTOGRAMS=Accessibility.OCR.Service.MemoryBefore.{status}.Available is replaced by Accessibility.{ServiceName}.Service.MaxMemoryLoad
OBSOLETE_HISTOGRAMS=Accessibility.OCR.Service.MemoryBefore.{status}.Pressure is replaced by Accessibility.{ServiceName}.Service.MaxMemoryLoad
OBSOLETE_HISTOGRAMS=Accessibility.OCR.Service.MemoryBefore.{status}.Total is replaced by Accessibility.{ServiceName}.Service.MaxMemoryLoad

AX-Relotes: n/a
Bug: 369722831
Change-Id: I23bfe03ef6f3db5d4739c38d04398ee272ce8534
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6552375
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Mark Schillaci <mschillaci@google.com>
Reviewed-by: Joe Mason <joenotcharles@google.com>
Reviewed-by: Kyungjun Lee <kyungjunlee@google.com>
Cr-Commit-Position: refs/heads/main@{#1464563}