Revert "De-couple PredictionMetricsHandler from specific histograms"

This reverts commit 1d11f9fd034ea02b7c1a913c2267ac9224ac7003.

Reason for revert: Suspect for failing test, InputHandlerProxyEventQueueTest.VSyncAlignedGestureScrollPinchScroll
https://ci.chromium.org/p/chromium/builders/ci/Linux%20ChromiumOS%20MSan%20Tests/20826

Original change's description:
> De-couple PredictionMetricsHandler from specific histograms
>
> PredictionMetricsHandler appears to be designed to work for anything
> that is predicting points. However, it currently only reports metrics
> in the Event.InputEventPrediction.Scroll* histograms. De-couple the
> class from these histograms so it can be used for things only than
> scroll metrics.
>
> Bug: 1133785
> Change-Id: Ib34129fc46b20b45810cbd5ca195483e88c513e2
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2441197
> Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
> Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
> Commit-Queue: Mario Bianucci <mabian@microsoft.com>
> Cr-Commit-Position: refs/heads/master@{#813813}

TBR=sadrul@chromium.org,dtapuska@chromium.org,mabian@microsoft.com

Change-Id: I9cefcdb1b51f13026726eb2449e1213f43dfc91f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1133785
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2451569
Reviewed-by: Kristi Park <kristipark@chromium.org>
Commit-Queue: Kristi Park <kristipark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813996}