Revert of WebView Guest should use ZOOM_MODE_ISOLATED.

Revert of WebView Guest should use ZOOM_MODE_ISOLATED. (patchset #2 id:100001 of https://codereview.chromium.org/645153002/)

Reason for revert:
This CL seems to be at the root of several other issues, including https://code.google.com/p/chromium/issues/detail?id=429004.

In particular, it seems to be allowing re-entrancy into ZoomController that was unexpected due to the timing with which OnGuestReady() is called.

Original issue's description:
> WebView Guest should use ZOOM_MODE_ISOLATED.
>
> In order that changes to zoom levels in a WebView Guest don't affect
> the embedder, set the WebView Guest's WebContents to use
> ZOOM_MODE_ISOLATED.
>
> BUG=418605
>
> Committed: https://crrev.com/f71a5dc79473cc74990d1e288c66ac282c2926a1
> Cr-Commit-Position: refs/heads/master@{#299493}

TBR=fsamuel@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=418605
Committed: https://crrev.com/82c6af625500a7bfdcf9f619c4e5702fa12f2b40
Cr-Commit-Position: refs/heads/master@{#302332}

[wjmaclean, 2014-10-31 21:38:21]

Created Revert of WebView Guest should use ZOOM_MODE_ISOLATED.

[commit-bot: I haz the power, 2014-10-31 21:39:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/690373002/1

[commit-bot: I haz the power, 2014-10-31 21:40:38]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-31 21:40:40]

Failed to apply patch for
chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc:
While running git apply --index -3 -p1;
  error: patch failed:
chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc:135
  Falling back to three-way merge...
  Applied patch to
'chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc' with
conflicts.
  U chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc

Patch:      
chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
Index: chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
diff --git
a/chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
b/chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
index
2a9680964558c9cae040026b761e66c3bd32861c..2bc3e42d6675d828fa8057294435e4631e6b4fae
100644
--- a/chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
+++ b/chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
@@ -135,13 +135,6 @@
     InjectChromeVoxIfNeeded(render_frame_host->GetRenderViewHost());
 }
 
-void ChromeWebViewGuestDelegate::OnGuestReady() {
-  ZoomController* zoom_controller =
-      ZoomController::FromWebContents(guest_web_contents());
-  DCHECK(zoom_controller);
-  zoom_controller->SetZoomMode(ZoomController::ZOOM_MODE_ISOLATED);
-}
-
 void ChromeWebViewGuestDelegate::OnGuestDestroyed() {
   // Clean up custom context menu items for this guest.
   extensions::MenuManager* menu_manager = extensions::MenuManager::Get(

[commit-bot: I haz the power, 2014-10-31 21:41:19]

The CQ bit was unchecked by commit-bot@chromium.org

[wjmaclean, 2014-10-31 21:58:16]

The CQ bit was checked by wjmaclean@chromium.org

[commit-bot: I haz the power, 2014-10-31 21:58:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/690373002/130001

[commit-bot: I haz the power, 2014-10-31 22:00:23]

Committed patchset #2 (id:130001)

[commit-bot: I haz the power, 2014-10-31 22:01:41]

Patchset 2 (id:??) landed as
https://crrev.com/82c6af625500a7bfdcf9f619c4e5702fa12f2b40
Cr-Commit-Position: refs/heads/master@{#302332}