GitLab

When running Pinpoint, and CQ Dry Runs of the GpuMemoryAblationExperiment
being enabled-by-default, a few issues were uncovered:
  - GrContexts cannot always be initialized (crbug.com/1103780)
  - Nested changes to GLContext during initialization fails
    (crbug.com/1104316)
  - Nested deletion crashes in mutually-exclusive ways
    (crbug.com/1106926)

This change looks to address these by restructuring how GpuMemoryAblationExperiment
performs its initialization and context switches.
  - The feature will now disable itself for Mock/Stub GL impls. This will
    prevent attempting to create GrContext in tests where it will always
    fail.
  - For initialization and allocation a ui::ScopedMakeContext will be
    used. This allows resetting of previous state so that GLContexts can
    properly initialize.
  - Deletion will now be done on a PostTask. While some deletion errors
    can be addressed by resetting the context. Resetting the context
    itself can lead to accessing partially deleted objects. Setting a
    a null Surface instead of a scoped context would address these cases,
    but do not address deletion paths that need their context set the
    entire time.

This update to initialization and context handling did help uncover other
issues (1107497, 1107502, 1107509, 1107512) however those are either
platforms we are not running Pinpoint on, or tied to specific test
suites. The root causes of these failures will be investigated
separately.

Bug: 1103780, 1104316, 1106926

Change-Id: Ibf3c9a3a560912f5505f99870b848878a99da5ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2300183
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Reviewed-by: Jonathan Backer <backer@chromium.org>
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792434}