Reland "LiteVideo: Stop throttling on playback seek events"

This is a reland of 0716d3fbd2eed132aa93006c94265c072d61d9b6

The failing test ran fine 100+ times in linux.
Could not repro the Mac failures, but I am removing the failing expect check.

Original change's description:
> LiteVideo: Stop throttling on playback seek events
>
> This plumbs the playback seek event from renderer to browser and uses it
> to stop litevideo throttling. The seek updates to browser are throttled
> for performance reasons.
>
> Subsequent CL will change this to stop throttling only after k seek
> events (finchable), and record this in UKM.
>
> Bug: 1134672
> Change-Id: Idd88819e8ae50ffbc215197a437bf87d6fa9a36a
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2453801
> Reviewed-by: Kinuko Yasuda <[email protected]>
> Reviewed-by: Michael Crouse <[email protected]>
> Reviewed-by: Dale Curtis <[email protected]>
> Commit-Queue: rajendrant <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#815787}

[email protected],[email protected],[email protected]

Bug: 1134672
Change-Id: Ic75af0f84e35515ae6fde3c2c44b9da782751d26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2467014
Reviewed-by: rajendrant <[email protected]>
Commit-Queue: rajendrant <[email protected]>
Cr-Commit-Position: refs/heads/master@{#816465}
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 78b40f9..c983e5e 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -8559,6 +8559,12 @@
   });
 }
 
+void WebContentsImpl::MediaPlayerSeek(const MediaPlayerId& id) {
+  OPTIONAL_TRACE_EVENT0("content", "WebContentsImpl::MediaPlayerSeek");
+  observers_.ForEachObserver(
+      [&](WebContentsObserver* observer) { observer->MediaPlayerSeek(id); });
+}
+
 void WebContentsImpl::MediaEffectivelyFullscreenChanged(bool is_fullscreen) {
   OPTIONAL_TRACE_EVENT1("content",
                         "WebContentsImpl::MediaEffectivelyFullscreenChanged",