Revert of Add ref-count on RenderViewHost for each new RenderFrameProxyHost.

Revert of Add ref-count on RenderViewHost for each new RenderFrameProxyHost. (patchset #4 id:60001 of https://codereview.chromium.org/1150793002/)

Reason for revert:
It looks like the new browser test fails on Win8 aura https://build.chromium.org/p/chromium.win/builders/Win8%20Aura/builds/30026/steps/content_browsertests/logs/RenderFrameHostManagerTest.CleanupOnCrossProcessNavigation

Original issue's description:
> Add ref-count on RenderViewHost for each new RenderFrameProxyHost.
>
> Currently, only RenderFrameHosts are ref-counting the associated RenderViewHost.
> Since it is possible to have a RenderViewHost with no associated RenderFrameHost
> (for example a cross-process window opener/openee relationship), it should
> be taken into account that the associated RenderFrameProxyHost is also
> a ref-counting the RenderViewHost.
> The goal of this CL is to allow for that, even though it isn't currently
> the case. It is a small step towards removing swapped out RenderFrameHosts.
>
> BUG=357747
>
> Committed: https://crrev.com/8542185bbb9fd0c0e7d0240c64403d2e4cea39f2
> Cr-Commit-Position: refs/heads/master@{#331016}

TBR=creis@chromium.org,nasko@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=357747
Committed: https://crrev.com/72e13b2f01beb6105c6a74b66aa92bdc6d553a8e
Cr-Commit-Position: refs/heads/master@{#331041}

[Steven Holte, 2015-05-22 01:24:44]

Created Revert of Add ref-count on RenderViewHost for each new
RenderFrameProxyHost.

[commit-bot: I haz the power, 2015-05-22 01:26:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1157563002/1

[commit-bot: I haz the power, 2015-05-22 01:30:57]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-22 01:31:47]

Patchset 1 (id:??) landed as
https://crrev.com/72e13b2f01beb6105c6a74b66aa92bdc6d553a8e
Cr-Commit-Position: refs/heads/master@{#331041}