RenderFrameImpl: extract a helper function, GetRoutingIdForFrameOrProxy().

RenderFrameImpl: extract a helper function, GetRoutingIdForFrameOrProxy().

The helper returns the routing ID of the RenderFrameImpl/RenderFrameProxy
associated with a remote or local WebFrame.

BUG=None
TEST=cq
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_site_isolation

Committed: https://crrev.com/8d7486dbb1438e26fddc3e9756329eeca2b56806
Cr-Commit-Position: refs/heads/master@{#353309}

[ncarter (slow), 2015-10-08 21:50:21]

The CQ bit was checked by nick@chromium.org to run a CQ dry run

[ncarter (slow), 2015-10-08 21:50:55]

The CQ bit was unchecked by nick@chromium.org

[ncarter (slow), 2015-10-08 21:51:50]

The CQ bit was checked by nick@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-10-08 21:54:37]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1398443004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1398443004/20001

[ncarter (slow), 2015-10-08 22:14:39]

nick@chromium.org changed reviewers:
+ dcheng@chromium.org

[ncarter (slow), 2015-10-08 22:14:39]

dcheng: PTAL. This pattern is starting to crop up in a few places, so it seems
worthwhile to add a helper.

[commit-bot: I haz the power, 2015-10-08 23:01:08]

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

[commit-bot: I haz the power, 2015-10-08 23:01:09]

Dry run: Try jobs failed on following builders:
  linux_site_isolation on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_site_isol...)

[dcheng, 2015-10-08 23:49:19]

lgtm

[Łukasz Anforowicz, 2015-10-09 15:50:12]

The CQ bit was checked by lukasza@chromium.org

[commit-bot: I haz the power, 2015-10-09 15:51:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1398443004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1398443004/20001

[commit-bot: I haz the power, 2015-10-09 16:39:30]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-09 16:40:53]

Patchset 2 (id:??) landed as
https://crrev.com/8d7486dbb1438e26fddc3e9756329eeca2b56806
Cr-Commit-Position: refs/heads/master@{#353309}