[PartitionAlloc] Additional code cleanup.

In https://chromium-review.googlesource.com/c/chromium/src/+/1607149, we did:

  This CL also does some code cleanup. This involved making sure we always
  observe `PartitionAllocReturnNull` in every case where
  `MEMORY_TOOL_REPLACES_ALLOCATOR` is defined; previously we did not.

But, we missed a spot. This CL fixes that.

Bug: None
Change-Id: I408fa95ca216a7a53196f2e9dae826190eef7a0a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1636709
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Chris Palmer <palmer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664574}
1 file changed