Revert "fix an instance of bugprone-unused-return-value"

This reverts commit cd0974ca.

Reason for revert: Causes a crash (crbug/1136605). We will assign crbug/1136605 to melzhang@ to implement this change safely.

Original change's description:
> fix an instance of bugprone-unused-return-value
>
> This new clang-tidy check fires when the result of a function like
> `unique_ptr.release()` is unused. Sometimes this is intentional, other
> times, it's not (e.g., the dev intended to `.reset()`).
>
> Bug: 1134714
> Change-Id: Ia6a272a8b45bfc3eace44d94f244cbfcedede608
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2457649
> Reviewed-by: Dominick Ng <dominickn@chromium.org>
> Commit-Queue: George Burgess <gbiv@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#815188}

TBR=gbiv@chromium.org,dominickn@chromium.org

Change-Id: I34a595e9773b1c9d28ce0fe713ca093625a5e2c9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1134714
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462629Reviewed-by: Josh Nohle <nohle@chromium.org>
Commit-Queue: Josh Nohle <nohle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815455}

chrome/browser/sharesheet/sharesheet_service_delegate.cc

@@ -37,7 +37,7 @@ void SharesheetServiceDelegate::ShowBubble(
 
 void SharesheetServiceDelegate::OnBubbleClosed(
     const base::string16& active_action) {
-  sharesheet_bubble_view_.reset();
+  sharesheet_bubble_view_.release();
   sharesheet_service_->OnBubbleClosed(id_, active_action);
 }