Revert of Fix crash when user closes window prior to the "Confirm Install" prompt showing

Revert of Fix crash when user closes window prior to the "Confirm Install" prompt showing (patchset #9 id:270001 of https://codereview.chromium.org/662073002/)

Reason for revert:
Broke test on the GPU waterfall http://build.chromium.org/p/chromium.gpu/builders/GPU%20Mac%20Builder%20%28dbg%29/builds/20292/steps/compile/logs/stdio

Original issue's description:
> Fix crash when user closes window prior to the "Confirm Install" prompt showing.
>
> This CL moves ExtensionInstallPrompt::ShowParams to its own class. The new class
> observes the content::WebContents and gfx::NativeWindow for their destruction.
>
> If the window is closed prior to the "Confirm Install" prompt showing, the
> prompt is shown as a non-modal free-standing dialog.
>
> BUG=422814
> TEST=ExtensionInstallPromptBrowserTest.*
>
> Committed: https://crrev.com/d53564d3743bc2da768b38f0db34090a7bb43fea
> Cr-Commit-Position: refs/heads/master@{#301674}

TBR=asargent@chromium.org,sky@chromium.org,thakis@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=422814
Committed: https://crrev.com/674e6a9f4dedcdd16530f3b5d99714a0595ab1c9
Cr-Commit-Position: refs/heads/master@{#301702}

[pkotwicz, 2014-10-28 20:38:50]

Created Revert of Fix crash when user closes window prior to the "Confirm
Install" prompt showing

[commit-bot: I haz the power, 2014-10-28 20:39:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/683993002/1

[commit-bot: I haz the power, 2014-10-28 20:41:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-28 20:42:09]

Patchset 1 (id:??) landed as
https://crrev.com/674e6a9f4dedcdd16530f3b5d99714a0595ab1c9
Cr-Commit-Position: refs/heads/master@{#301702}