Use base::BindOnce() and OnceClosure for a callback only run once.

R=bokan@chromium.org

Bug: 954011, 1028284
Change-Id: I852b389c12b5bb96cbe2bdef52516b546fe6fdb2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1934651
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719177}

cc/input/scrollbar_controller.cc

@@ -112,12 +112,12 @@ InputHandlerPointerResult ScrollbarController::HandlePointerDown(
     // have the potential of initiating an autoscroll (if held down for long
     // enough).
     DCHECK(scrollbar_part != ScrollbarPart::THUMB);
-    cancelable_autoscroll_task_ = std::make_unique<base::CancelableClosure>(
-        base::Bind(&ScrollbarController::StartAutoScrollAnimation,
-                   base::Unretained(this),
-                   InitialDeltaToAutoscrollVelocity(
-                       scrollbar, scroll_result.scroll_offset),
-                   scrollbar, scrollbar_part));
+    cancelable_autoscroll_task_ = std::make_unique<base::CancelableOnceClosure>(
+        base::BindOnce(&ScrollbarController::StartAutoScrollAnimation,
+                       base::Unretained(this),
+                       InitialDeltaToAutoscrollVelocity(
+                           scrollbar, scroll_result.scroll_offset),
+                       scrollbar, scrollbar_part));
     layer_tree_host_impl_->task_runner_provider()
         ->ImplThreadTaskRunner()
         ->PostDelayedTask(FROM_HERE, cancelable_autoscroll_task_->callback(),

cc/input/scrollbar_controller.h

@@ -177,7 +177,7 @@ class CC_EXPORT ScrollbarController {
   // pointermoves are not VSync aligned).
   bool drag_processed_for_current_frame_;
 
-  std::unique_ptr<base::CancelableClosure> cancelable_autoscroll_task_;
+  std::unique_ptr<base::CancelableOnceClosure> cancelable_autoscroll_task_;
 };
 
 }  // namespace cc