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

Review URL: https://codereview.chromium.org/1637313002

Cr-Commit-Position: refs/heads/master@{#371724}

ui/accelerated_widget_mac/display_link_mac.cc

@@ -86,14 +86,6 @@ DisplayLinkMac::DisplayLinkMac(
 DisplayLinkMac::~DisplayLinkMac() {
   StopDisplayLink();
 
-  // Usually |display_link_| holds the last reference to CVDisplayLinkRef, but
-  // that's not guaranteed, so it might not free all resources after the
-  // destructor completes. Ensure the callback is cleared out regardless to
-  // avoid possible crashes (see http://crbug.com/564780).
-  CVReturn ret =
-      CVDisplayLinkSetOutputCallback(display_link_, nullptr, nullptr);
-  DCHECK_EQ(kCGErrorSuccess, ret);
-
   DisplayMap::iterator found = display_map_.Get().find(display_id_);
   DCHECK(found != display_map_.Get().end());
   DCHECK(found->second == this);