Detect and clean up discarded mojo connections to deleted RenderFrames.

Detect and clean up discarded mojo connections to deleted RenderFrames.

Currently, if a RenderFrame is deleted before the
ExchangeServiceProviders message is received in the renderer, the
message pipe handles contained in that message are retained, waiting for
a RenderFrame that has already been deleted. This changes
RenderThreadImpl::PendingRenderFrameConnect to detect when the browser
closes its handles to those message pipes and clean itself up when that
occurs.

BUG=457722
Committed: https://crrev.com/00150c1b3233c1d634deec284906653a4b7a2a92
Cr-Commit-Position: refs/heads/master@{#320690}

[Sam McNally, 2015-03-13 08:03:26]

sammc@chromium.org changed reviewers:
+ avi@chromium.org

[Avi (use Gerrit), 2015-03-13 13:54:08]

lgtm with nit

https://codereview.chromium.org/1005893002/diff/1/content/renderer/render_thr...
File content/renderer/render_thread_impl.cc (right):

https://codereview.chromium.org/1005893002/diff/1/content/renderer/render_thr...
content/renderer/render_thread_impl.cc:1812: DCHECK_EQ(erased, 1u);
Put the expected value first; if the DCHECK fails, the error message will read
correctly.

[Sam McNally, 2015-03-15 22:28:19]

https://codereview.chromium.org/1005893002/diff/1/content/renderer/render_thr...
File content/renderer/render_thread_impl.cc (right):

https://codereview.chromium.org/1005893002/diff/1/content/renderer/render_thr...
content/renderer/render_thread_impl.cc:1812: DCHECK_EQ(erased, 1u);
On 2015/03/13 13:54:07, Avi wrote:
> Put the expected value first; if the DCHECK fails, the error message will read
> correctly.

Done.

[Sam McNally, 2015-03-15 22:28:50]

The CQ bit was checked by sammc@chromium.org

[Sam McNally, 2015-03-15 22:28:50]

The patchset sent to the CQ was uploaded after l-g-t-m from avi@chromium.org
Link to the patchset: https://codereview.chromium.org/1005893002/#ps20001
(title: "DCHECK_EQ(1u, erased)")

[commit-bot: I haz the power, 2015-03-15 22:28:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1005893002/20001

[commit-bot: I haz the power, 2015-03-15 23:26:01]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-03-15 23:26:54]

Patchset 2 (id:??) landed as
https://crrev.com/00150c1b3233c1d634deec284906653a4b7a2a92
Cr-Commit-Position: refs/heads/master@{#320690}