GuestViewContainer lifetime should only be managed by BrowserPlugin and not RenderFrameObserver

GuestViewContainer lifetime should only be managed by BrowserPlugin and not RenderFrameObserver

This prevents racy teardowns that might cause BrowserPlugin to try to delete an invalid
pointer

BUG=none
Test=Open browser sample, and close browser sample. It should not crash.
TBR=lazyboy@chromium.org

Committed: https://crrev.com/b4e3817fa26c6c53ea930beab249c51d0370bd31
Cr-Commit-Position: refs/heads/master@{#295127}

[Fady Samuel, 2014-09-16 17:12:47]

fsamuel@chromium.org changed reviewers:
+ lazyboy@chromium.org

[Fady Samuel, 2014-09-16 17:19:36]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2014-09-16 17:22:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/574623004/20001

[lazyboy, 2014-09-16 17:34:44]

lgtm

[commit-bot: I haz the power, 2014-09-16 19:41:56]

Committed patchset #2 (id:20001) as 1e8b7f4c9d5e155e7532c78bb04bb37f8b3af636

[commit-bot: I haz the power, 2014-09-16 19:43:16]

Patchset 2 (id:??) landed as
https://crrev.com/b4e3817fa26c6c53ea930beab249c51d0370bd31
Cr-Commit-Position: refs/heads/master@{#295127}