Cherry pick PR #9808: zlib: Fix GzipCompress invalid pointer crash

[cobalt-github-releaser-bot]

Refer to the original PR: #9808

GzipCompress crashed in a CobaltMetricsLogUploaderTest test
due to a mismatched memory allocator issue.

The initial buffer was allocated using base::UncheckedMalloc,
which routes through PartitionAlloc. However, subsequent resizing
attempted to use the system realloc(), causing a SIGABRT.

This change avoids realloc() and correctly pairs base::UncheckedFree()
with base::UncheckedMalloc() to resolve the invalid pointer abort.

Bug: 486012022
Bug: 486003653
Bug: 502259405

[cobalt-github-releaser-bot]

Caution

There were merge conflicts while cherry picking! Check out cherry-pick-main-9808 and fix the conflicts before proceeding. Check the log at https://github.com/youtube/cobalt/actions/runs/24411862760 for details.

[github-actions]

🤖 Gemini Suggested Commit Message

---

cobalt: Fix GzipCompress invalid pointer crash

The GzipCompress function crashed in Cobalt due to mismatched memory
allocators. An initial buffer allocated with base::UncheckedMalloc (via
PartitionAlloc) was incorrectly reallocated using the system realloc(),
leading to a SIGABRT. This change ensures that for Cobalt builds,
GzipCompress uses base::UncheckedFree() and avoids realloc(), thus
correctly pairing memory operations and resolving the invalid pointer
abort.

Bug: 486012022
Bug: 486003653
Bug: 502259405

---

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