memory-infra: Pickle doesn't necessary align with kPickleHeapAlign
memory-infra: Pickle doesn't necessary align with kPickleHeapAlign

Pickle::ClaimUninitializedBytesInternal() uses kPicleHeapAlign only when
|new_capacity| is greater than kPickleHeapAlign. This means that if
a TracedValue is small, we could over-estimate tracing overhead.
Since Pickle uses GetTotalAllocatedSize() to realloc, we can simply
report GetTotalAllocatedSize() (and size()) as overhead.

BUG=583252

Review URL: https://codereview.chromium.org/1866913002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#386539}

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