[tracing] Fix single-process detection logic of ChildTraceMessageFilter

[tracing] Fix single-process detection logic of ChildTraceMessageFilter

Currently the instantiation of ChildTraceMessageFilter in
child_thread_impl.cc is guarded by a check on
CommandLine.HasSwitch(kSingleProcess)
The rationale is that in single-process mode we don't want to have any
message filter as the browser-side tracing will cover all the threads.
However, the aforementioned check is not complete, as it does not
covers the case of tests using the InProcessUtilityThreadHelper [1].
In those tests, the kSingleProcess flag is not present, but the
renderer is in-process anyways.
Replacing the the HasSwitch check in with IsInBrowserProcess(),
which covers also the latter case.

[1] for instance extensions/browser/sandboxed_unpacker_unittest.cc

BUG=474973
Committed: https://crrev.com/4950a30243ae4573b78033781830a113d220f938
Cr-Commit-Position: refs/heads/master@{#324276}

[Primiano Tucci (use gerrit), 2015-04-08 11:06:39]

primiano@chromium.org changed reviewers:
+ avi@chromium.org, nduca@chromium.org

[Primiano Tucci (use gerrit), 2015-04-08 12:07:26]

PTAL, it's just a one line change.

[Avi (use Gerrit), 2015-04-08 14:42:35]

lgtm; nit

https://codereview.chromium.org/1069253003/diff/1/base/trace_event/memory_dum...
File base/trace_event/memory_dump_manager.cc (right):

https://codereview.chromium.org/1069253003/diff/1/base/trace_event/memory_dum...
base/trace_event/memory_dump_manager.cc:80: DCHECK(delegate_ == nullptr);
DCHECK_EQ(nullptr, delegate);

[Primiano Tucci (use gerrit), 2015-04-08 15:04:29]

https://codereview.chromium.org/1069253003/diff/1/base/trace_event/memory_dum...
File base/trace_event/memory_dump_manager.cc (right):

https://codereview.chromium.org/1069253003/diff/1/base/trace_event/memory_dum...
base/trace_event/memory_dump_manager.cc:80: DCHECK(delegate_ == nullptr);
On 2015/04/08 14:42:35, Avi wrote:
> DCHECK_EQ(nullptr, delegate);

Yeah, I was just too lazy to do the cast.
Unfortunately you can't just DCHECK_EQ(nullptr,stuff) as it will fail to find
the right template expansion (with a nice 10 pages error).
This is the only way I know of using DCHECK_EQ with nullptr.

[Avi (use Gerrit), 2015-04-08 15:20:19]

https://codereview.chromium.org/1069253003/diff/1/base/trace_event/memory_dum...
File base/trace_event/memory_dump_manager.cc (right):

https://codereview.chromium.org/1069253003/diff/1/base/trace_event/memory_dum...
base/trace_event/memory_dump_manager.cc:80: DCHECK(delegate_ == nullptr);
On 2015/04/08 15:04:29, Primiano Tucci wrote:
> On 2015/04/08 14:42:35, Avi wrote:
> > DCHECK_EQ(nullptr, delegate);
> 
> Yeah, I was just too lazy to do the cast.
> Unfortunately you can't just DCHECK_EQ(nullptr,stuff) as it will fail to find
> the right template expansion (with a nice 10 pages error).
> This is the only way I know of using DCHECK_EQ with nullptr.

That's surprising; I've done it quite a bit. You couldn't do it with NULL, but
nullptr should work.

[nduca, 2015-04-08 16:06:21]

lgtm

[Primiano Tucci (use gerrit), 2015-04-08 17:53:24]

The CQ bit was checked by primiano@chromium.org

[Primiano Tucci (use gerrit), 2015-04-08 17:53:24]

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/1069253003/#ps20001
(title: "Fix DCHECK_EQ")

[commit-bot: I haz the power, 2015-04-08 17:54:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1069253003/20001

[commit-bot: I haz the power, 2015-04-08 20:06:51]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-08 20:07:48]

Patchset 2 (id:??) landed as
https://crrev.com/4950a30243ae4573b78033781830a113d220f938
Cr-Commit-Position: refs/heads/master@{#324276}