Fix RenderFrameProxyHost leak.

Fix RenderFrameProxyHost leak.

This was a regression that started with https://codereview.chromium.org/1055203002/

The test here was a gift from lfg@

BUG=475265
Committed: https://crrev.com/59dcb167ab88fd1c267e29304b1d4e43c58c2894
Cr-Commit-Position: refs/heads/master@{#324497}

[ncarter (slow), 2015-04-09 16:46:18]

nick@chromium.org changed reviewers:
+ creis@chromium.org, lfg@chromium.org

[ncarter (slow), 2015-04-09 16:46:18]

nick@chromium.org changed required reviewers:
+ creis@chromium.org

[ncarter (slow), 2015-04-09 16:46:18]

Charlie, please take a look.

This fixes the regression. There were other tests that exercised the bug, but
they didn't have strong enough asserts. In a subsequent CL I'll introduce a
tree-printer that will enhance those other tests so they would have caught this
bug.

[Charlie Reis, 2015-04-09 16:58:08]

[+site-isolation-reviews]

Thanks!  LGTM with nit.

https://codereview.chromium.org/1074843002/diff/40001/content/browser/site_pe...
File content/browser/site_per_process_browsertest.h (right):

https://codereview.chromium.org/1074843002/diff/40001/content/browser/site_pe...
content/browser/site_per_process_browsertest.h:19: // Returns an
alphabetically-sorted list of the site instance URLs
nit:s/site instance URLs/SiteInstance site URLs/
Also mention that they're one per line (since one might expect this to return a
list of strings).

[ncarter (slow), 2015-04-09 17:31:30]

The CQ bit was checked by nick@chromium.org

[ncarter (slow), 2015-04-09 17:31:30]

The patchset sent to the CQ was uploaded after l-g-t-m from creis@chromium.org
Link to the patchset: https://codereview.chromium.org/1074843002/#ps60001
(title: "Add comment suggested by Charlie")

[commit-bot: I haz the power, 2015-04-09 17:32:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1074843002/60001

[commit-bot: I haz the power, 2015-04-09 20:29:13]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-04-09 20:30:11]

Patchset 4 (id:??) landed as
https://crrev.com/59dcb167ab88fd1c267e29304b1d4e43c58c2894
Cr-Commit-Position: refs/heads/master@{#324497}