ExtensionFunctionDispatcher should use base::Process::Current() if single process mode.

ExtensionFunctionDispatcher should use base::Process::Current() if single process
mode.

Since #323179, ExtensionFunctionDispatcher has used
base::Process::DeprecatedGetProcessFromHandle to callback:
https://chromium.googlesource.com/chromium/src/+/f8d789c4558c7575f4d388d44730d18fdf157
72c
However, base::Process::DeprecatedGetProcessFromHandle(handle) assumes
 |handle| is not current process handle. The assumption brakes if single process mode
 thus chrome can't start with the '--single-process' flag.

BUG=477001
Committed: https://crrev.com/f71a0add64e543c7bb4cf59442b77ec5f3f6978e
Cr-Commit-Position: refs/heads/master@{#328923}

[yoichio, 2015-05-01 07:48:40]

yoichio@chromium.org changed reviewers:
+ cpu@chromium.org, rvargas@chromium.org

[cpu_(ooo_6.6-7.5), 2015-05-01 17:21:41]

please use an extensions owner.

[cpu_(ooo_6.6-7.5), 2015-05-08 02:56:49]

on second thought this seems easy enough for me to review.

lgtm

[cpu_(ooo_6.6-7.5), 2015-05-08 02:57:17]

lgtm

[cpu_(ooo_6.6-7.5), 2015-05-08 02:57:21]

The CQ bit was checked by cpu@chromium.org

[commit-bot: I haz the power, 2015-05-08 02:57:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1113343002/1

[commit-bot: I haz the power, 2015-05-08 04:03:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-08 04:05:34]

Patchset 1 (id:??) landed as
https://crrev.com/f71a0add64e543c7bb4cf59442b77ec5f3f6978e
Cr-Commit-Position: refs/heads/master@{#328923}