Revert of Speculative fix for ui::DisplayLinkMac::StopDisplayLink crashes

Revert of Speculative fix for ui::DisplayLinkMac::StopDisplayLink crashes (patchset #2 id:20001 of https://codereview.chromium.org/1626163002/ )

Reason for revert:
Broke compile:
../../ui/accelerated_widget_mac/display_link_mac.cc:94:69: error: null passed to a callee that requires a non-null argument [-Werror,-Wnonnull]
      CVDisplayLinkSetOutputCallback(display_link_, nullptr, nullptr);
                                                    ~~~~~~~         ^

Original issue's description:
> Speculative fix for ui::DisplayLinkMac::StopDisplayLink crashes
>
> The CVDisplayLink is tied to a ScopedTypeRef data member of DisplayLinkMac.
> However, there may be other references. Since there's no guarantee that
> ~DisplayLinkMac() will invoke the last CVDisplayLinkRelease(..) and clear
> the callback automatically, clear it explicitly in ~DisplayLinkMac.
>
> BUG=564780
>
> Committed: https://crrev.com/2286ddf0119516f7a93feaff4f8ce2edff8c4543
> Cr-Commit-Position: refs/heads/master@{#371648}

TBR=ccameron@chromium.org,tapted@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=564780
Committed: https://crrev.com/40b4841e82e2a559ffa94173d83e95ea3a64e146
Cr-Commit-Position: refs/heads/master@{#371724}

[pdr., 2016-01-27 04:30:28]

Created Revert of Speculative fix for ui::DisplayLinkMac::StopDisplayLink
crashes

[commit-bot: I haz the power, 2016-01-27 04:30:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1637313002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1637313002/1

[commit-bot: I haz the power, 2016-01-27 04:32:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1637313002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1637313002/1

[commit-bot: I haz the power, 2016-01-27 04:36:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-01-27 04:37:32]

Description was changed from

==========
Revert of Speculative fix for ui::DisplayLinkMac::StopDisplayLink crashes
(patchset #2 id:20001 of https://codereview.chromium.org/1626163002/ )

Reason for revert:
Broke compile:
../../ui/accelerated_widget_mac/display_link_mac.cc:94:69: error: null passed to
a callee that requires a non-null argument [-Werror,-Wnonnull]
      CVDisplayLinkSetOutputCallback(display_link_, nullptr, nullptr);
                                                    ~~~~~~~         ^


Original issue's description:
> Speculative fix for ui::DisplayLinkMac::StopDisplayLink crashes
> 
> The CVDisplayLink is tied to a ScopedTypeRef data member of DisplayLinkMac.
> However, there may be other references. Since there's no guarantee that
> ~DisplayLinkMac() will invoke the last CVDisplayLinkRelease(..) and clear
> the callback automatically, clear it explicitly in ~DisplayLinkMac.
> 
> BUG=564780
> 
> Committed: https://crrev.com/2286ddf0119516f7a93feaff4f8ce2edff8c4543
> Cr-Commit-Position: refs/heads/master@{#371648}

TBR=ccameron@chromium.org,tapted@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=564780
==========

to

==========
Revert of Speculative fix for ui::DisplayLinkMac::StopDisplayLink crashes
(patchset #2 id:20001 of https://codereview.chromium.org/1626163002/ )

Reason for revert:
Broke compile:
../../ui/accelerated_widget_mac/display_link_mac.cc:94:69: error: null passed to
a callee that requires a non-null argument [-Werror,-Wnonnull]
      CVDisplayLinkSetOutputCallback(display_link_, nullptr, nullptr);
                                                    ~~~~~~~         ^

Original issue's description:
> Speculative fix for ui::DisplayLinkMac::StopDisplayLink crashes
>
> The CVDisplayLink is tied to a ScopedTypeRef data member of DisplayLinkMac.
> However, there may be other references. Since there's no guarantee that
> ~DisplayLinkMac() will invoke the last CVDisplayLinkRelease(..) and clear
> the callback automatically, clear it explicitly in ~DisplayLinkMac.
>
> BUG=564780
>
> Committed: https://crrev.com/2286ddf0119516f7a93feaff4f8ce2edff8c4543
> Cr-Commit-Position: refs/heads/master@{#371648}

TBR=ccameron@chromium.org,tapted@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=564780

Committed: https://crrev.com/40b4841e82e2a559ffa94173d83e95ea3a64e146
Cr-Commit-Position: refs/heads/master@{#371724}
==========

[commit-bot: I haz the power, 2016-01-27 04:37:33]

Patchset 1 (id:??) landed as
https://crrev.com/40b4841e82e2a559ffa94173d83e95ea3a64e146
Cr-Commit-Position: refs/heads/master@{#371724}