Revert of skstd -> std for unique_ptr (patchset #16 id:300001 of https://codereview...

Revert of skstd -> std for unique_ptr (patchset #16 id:300001 of https://codereview.chromium.org/1436033003/ )

Reason for revert:
Test-iOS-Clang-iPad4-GPU-SGX554-Arm7-Release

Original issue's description:
> skstd -> std for unique_ptr
>
> TBR=reed@google.com
> No public API changes.
>
> BUG=skia:4564
>
> Committed: https://skia.googlesource.com/skia/+/755c553c17b82bb5de3d9cc8d3b2a866ff9e9e50
>
> CQ_EXTRA_TRYBOTS=client.skia.compile:Build-Mac10.9-Clang-x86_64-Release-CMake-Trybot,Build-Ubuntu-GCC-x86_64-Debug-CrOS_Link-Trybot;client.skia:Perf-Mac10.9-Clang-MacMini6.2-CPU-AVX-x86_64-Release-Trybot
>
> Committed: https://skia.googlesource.com/skia/+/06189155d987db5c7e69015f6ea87c2168d6a065
>
> Committed: https://skia.googlesource.com/skia/+/70e8dfca4a7f5bce97b8021a6e378c4828b09c8c

TBR=bungeman@google.com,mtklein@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:4564

Review URL: https://codereview.chromium.org/1482343002