Use CrossThreadBindOnce in HtmlVideoElementCapturerSource::sendNewFrame

... when posting tasks. A task posted runs once, so
CrossThreadBindRepeating is not strictly correct.

This is now possible, after [1].

[1] crrev.com/c/1750043

BUG=964922
R=jbroman@chromium.org

Change-Id: Ic3a7cf2fbcd6c07b92efaeab206e45a0cd1e418f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1752077
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686615}

third_party/blink/renderer/modules/mediacapturefromelement/html_video_element_capturer_source.cc

@@ -192,12 +192,9 @@ void HtmlVideoElementCapturerSource::sendNewFrame() {
     // Post with CrossThreadBind here, instead of CrossThreadBindOnce,
     // otherwise the |new_frame_callback_| ivar can be nulled out
     // unintentionally.
-    //
-    // TODO(crbug.com/964922): Consider cloning |new_frame_callback_|
-    // and use CrossThreadBind
     PostCrossThreadTask(
         *io_task_runner_, FROM_HERE,
-        CrossThreadBindRepeating(new_frame_callback_, frame, current_time));
+        CrossThreadBindOnce(new_frame_callback_, frame, current_time));
   }
 
   // Calculate the time in the future where the next frame should be created.