Revert of [blink] Unique pointers in Platform.h

Revert of [blink] Unique pointers in Platform.h (patchset #8 id:140001 of https://codereview.chromium.org/2846843002/ )

Reason for revert:
More cast audio linux compile failures.

Original issue's description:
> [blink] Unique pointers in Platform.h
> 
> Make Platform::*Create methods return a unique_ptr instead of a raw pointer
> to explictly state ownership logic.
> CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
> 
> Review-Url: https://codereview.chromium.org/2846843002
> Cr-Original-Commit-Position: refs/heads/master@{#467710}
> Committed: https://chromium.googlesource.com/chromium/src/+/d548cc04b6568f8edc08853940134707fcd6c455
> Review-Url: https://codereview.chromium.org/2846843002
> Cr-Commit-Position: refs/heads/master@{#468697}
> Committed: https://chromium.googlesource.com/chromium/src/+/bd3351963fb4da3e31478d841b91a117583f9786

TBR=haraken@chromium.org,clamy@chromium.org,tdresser@chromium.org,thakis@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2859553002
Cr-Commit-Position: refs/heads/master@{#468707}
Committed: https://chromium.googlesource.com/chromium/src/+/d9756b54c99d874bb9143d1c2113ad3c44710a61

[altimin, 2017-05-02 18:06:32]

The CQ bit was checked by altimin@chromium.org

[altimin, 2017-05-02 18:06:33]

Created Revert of [blink] Unique pointers in Platform.h

[commit-bot: I haz the power, 2017-05-02 18:06:54]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-02 18:08:26]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493748392708260, "parent_rev":
"67298a699946b1d43bd6babb062f87577a2a730d", "commit_rev":
"d9756b54c99d874bb9143d1c2113ad3c44710a61"}

[commit-bot: I haz the power, 2017-05-02 18:09:01]

Description was changed from

==========
Revert of [blink] Unique pointers in Platform.h (patchset #8 id:140001 of
https://codereview.chromium.org/2846843002/ )

Reason for revert:
More cast audio linux compile failures.

Original issue's description:
> [blink] Unique pointers in Platform.h
> 
> Make Platform::*Create methods return a unique_ptr instead of a raw pointer
> to explictly state ownership logic.
>
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
> 
> Review-Url: https://codereview.chromium.org/2846843002
> Cr-Original-Commit-Position: refs/heads/master@{#467710}
> Committed:
https://chromium.googlesource.com/chromium/src/+/d548cc04b6568f8edc0885394013...
> Review-Url: https://codereview.chromium.org/2846843002
> Cr-Commit-Position: refs/heads/master@{#468697}
> Committed:
https://chromium.googlesource.com/chromium/src/+/bd3351963fb4da3e31478d841b91...

TBR=haraken@chromium.org,clamy@chromium.org,tdresser@chromium.org,thakis@chro...
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
==========

to

==========
Revert of [blink] Unique pointers in Platform.h (patchset #8 id:140001 of
https://codereview.chromium.org/2846843002/ )

Reason for revert:
More cast audio linux compile failures.

Original issue's description:
> [blink] Unique pointers in Platform.h
> 
> Make Platform::*Create methods return a unique_ptr instead of a raw pointer
> to explictly state ownership logic.
>
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
> 
> Review-Url: https://codereview.chromium.org/2846843002
> Cr-Original-Commit-Position: refs/heads/master@{#467710}
> Committed:
https://chromium.googlesource.com/chromium/src/+/d548cc04b6568f8edc0885394013...
> Review-Url: https://codereview.chromium.org/2846843002
> Cr-Commit-Position: refs/heads/master@{#468697}
> Committed:
https://chromium.googlesource.com/chromium/src/+/bd3351963fb4da3e31478d841b91...

TBR=haraken@chromium.org,clamy@chromium.org,tdresser@chromium.org,thakis@chro...
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2859553002
Cr-Commit-Position: refs/heads/master@{#468707}
Committed:
https://chromium.googlesource.com/chromium/src/+/d9756b54c99d874bb9143d1c2113...
==========

[commit-bot: I haz the power, 2017-05-02 18:09:03]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/d9756b54c99d874bb9143d1c2113...

[haraken, 2017-05-03 00:42:50]

LGTM