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This reverts commit 258ed8d5.

Reason for revert: Suspect this introduced memory leaks and broke https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/WebKit%20Linux%20Trusty%20Leak/30388

Original change's description:
> Synthetic input waits on compositor display
> 
> This CL makes synthetic input - the kind used in web tests and
> telemetry (e.g. gpuBenchmarking.scrollBy) - wait until a CompositorFrame
> has been submitted by the renderer and displayed by the display
> compositor before resolving the completion callback. This means client
> code that wants to wait until any observable side-effects of this input
> is visible to further input need only wait on the gesture's completion
> callback.
> 
> To give a motivating example: suppose we wish to write a test that
> scrolls an out-of-process iframe into view and clicks on a button in the
> frame. The code might look something like this:
> 
> gpuBenchmarking.smoothScroll(1000, () => {
>   gpuBenchmarking.tap(0, 0);
> });
> 
> This code contains a race today. The callback for smoothScroll is
> invoked as soon as the ScrollEnd is received in the renderer. However,
> until a new compositor frame is submitted from the renderer, the tap
> may occur against stale hit testing geometry. This is a major source of
> flakiness in our tests.
> 
> This CL fixes the problem by forcing the renderer to perform a full
> redraw at the end of each gesture. The redraw produces a compositor
> frame and we invoke the callback once the compositor frame is displayed.
> We do this by reusing the RequestPresentation mechanism in RenderWidget.
> RequestPresentation required two modifications to work in web tests
> which use a single thread proxy with no scheduler:
> 
>  - LayerTreeHost::Composite needs to check the forced redraw flag to
>    determine whether we need to raster, otherwise it won't produce a
>    frame
>  - RequestPresentation must request a main frame since there's no
>    scheduler to perform the commit, which is what SetNeedsForcedRedraw
>    requests.
> 
> The timing change exposed an issue in the
> overlay-play-button-tap-to-hide.html test so this CL also cleans that
> test up to listen to the animation changes in media controls properly.
> 
> Finally, it's possible we may get input in a RenderWidget that's not
> currently displayed. e.g. A click event sent via ChromeDriver causes a
> TouchStart followed by a TouchEnd. The TouchStart causes a window.open
> which opens and focuses a new tab. The TouchEnd then happens on the
> background tab. In this case, we should resolve the callback rather than
> waiting on a CompositorFrame that'll never come. See ChromeDriver test
> testNetworkConnectionTypeIsAppliedToAllTabs for an example of this.
> 
> Bug: 902446
> Change-Id: Ib2dddee08400dfa1137c674c47c0d7106961162f
> Reviewed-on: https://chromium-review.googlesource.com/c/1390329
> Reviewed-by: Saman Sami <samans@chromium.org>
> Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
> Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
> Commit-Queue: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#633753}

TBR=danakj@chromium.org,bokan@chromium.org,dtapuska@chromium.org,nzolghadr@chromium.org,samans@chromium.org

Change-Id: I7a479a4af8fbec4b4452ff6d9d7b5b9df246f4a4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 902446
Reviewed-on: https://chromium-review.googlesource.com/c/1479370Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#633782}