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This reverts commit 1c6f831f.

Reason for revert: Revert due to FindIt analysis.

Original change's description:
> Don't SetVisible on swapped out RenderWidgets, and drop gpu resources.
> 
> When a RenderWidget is created for a RenderViewImpl, it may be
> considered "swapped out". This means the main frame for this
> RenderView's frame tree is not local, the RenderView exists to
> hold some other local subframe, which will be composited and have
> a RenderWidget. Thus the RenderWidget attached to the RenderViewImpl
> is not actually used, there is no output from the remote main frame
> in this tree. I like to refer to these swapped out RenderWidgets as
> zombies.
> 
> During navigations, a RenderViewImpl's main frame may change to or
> from being local, in which case the RenderWidget attached to it changes
> to or from being a zombie.
> 
> When becoming a zombie, the WebFrameWidget attached to the
> RenderViewImpl (wrapping the WebViewImpl) is destroyed, and this
> marks the compositor as SetVisible(false) on the RenderWidget
> (via the WebViewImpl).
> 
> When becoming alive again, a new WebFrameWidget is attached to the
> RenderViewImpl, and the WebFrameWidget marks the compositor as
> SetVisible(true) on the RenderWidget (via the WebViewImpl).
> 
> While a zombie, the WebViewImpl is also told not to allow any
> visibility changes to be passed along to the RenderWidget. This is
> because as the local subframe becomes visible with the Page, we'd
> tell the WebView about this, to tell the Page. But since the
> WebView now has a zombie RenderWidget, it shouldn't also tell that.
> 
> Note when the RenderViewImpl is created and initially swapped out
> it creates a RenderWidget but nothing tells its compositor about the
> zombie state of affairs, so it becomes visible, which makes it
> acquire a Gpu channel and start its scheduler etc. Woops.
> 
> This CL rearranges things a bit.
> - A new RenderWidget does not SetVisible(true) if swapped out.
> - RenderViewImpl directly marks it SetVisible(false) when removing the
> WebFrameWidget.
> - RenderViewImpl *also* removes the LayerTreeFrameSink to drop the
> Gpu channel since we don't need to be fast at becoming visible (the
> RenderWidget is a zombie!)
> - RenderViewImpl directly marks it as SetVisible(true) when getting
> a new WebFrameWidget as the RenderWidget stops being a zombie.
> - WebViewImpl stops calling SetVisible on the RenderWidget when its
> main frame is not visible. In the future the RenderWidget should be
> a member of the main LocalFrame, and thus won't even exist when the
> main frame is not local.
> 
> R=​dcheng@chromium.org, piman@chromium.org
> 
> Change-Id: I87a5d0dfeaaf08cb91c9348b26b4205db55b3a81
> Bug: 894899, 419087
> Reviewed-on: https://chromium-review.googlesource.com/c/1290140
> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Reviewed-by: Antoine Labour <piman@chromium.org>
> Commit-Queue: danakj <danakj@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#602389}

TBR=danakj@chromium.org,dcheng@chromium.org,piman@chromium.org

Change-Id: I2ec1cc5c7bfa723f4fafea7efe01d38ae5019532
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 894899, 419087
Reviewed-on: https://chromium-review.googlesource.com/c/1298330Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602428}