Move tracing namespace from base::debug to base::trace_event.

Move tracing namespace from base::debug to base::trace_event.

After having transitioned all the tracing headers from base/debug/ to
base/trace_event, this CL addresses the namespace move.
In principle, this CL should only change the namespace of the
base/trace_event files but the namespace used by the tracing clients.
In order to achieve this, namespace aliases are appended to the
trace_event headers, to make it so that clients can still refer to
base::debug::TraceFoo, with that being aliased to
base::trace_event::TraceFoo.
The upcoming CLs will gradually migrate the clients to use the
base::trace_event namespace and will remove the ns aliases.
Unfortunately, this CL has also to update few tracing clients,
in particular the ones having forward declarations. Forward
declarations, in fact, cannot be aliased as the compiler sees them
before the alias itself.

See crrev.com/837303004 and the related bug for motivations and design doc.

BUG=451032
TBR=skyostil@chromium.org,jam@chromium.org

Committed: https://crrev.com/97c5abba36f5ce473cd996fab74fbf5aa9bb5464
Cr-Commit-Position: refs/heads/master@{#314657}

[ssid, 2015-01-27 13:32:25]

ssid@chromium.org changed reviewers:
+ picksi@chromium.org, primiano@chromium.org, skyostil@chromium.org

[ssid, 2015-01-27 13:32:26]

PTAL at this change. Sorry for so many CL mails earlier.

[Primiano Tucci (use gerrit), 2015-01-27 14:34:11]

Almost there, just nits here and there.
Please add a 
"TODO(ssid): this is temporary, to handle the namespace migration, and should be
removed by Feb 2015. See crbug.com/451032"

Before the namespace migration and fwd declaration lines.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event.h
File base/trace_event/trace_event.h (right):

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event.h:1597: namespace base {
Can you please add a TODO(ssid) which a refernce to the bug to explain that this
forwarding is temporary to handle the transition gradually?

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
File base/trace_event/trace_event_android.cc (right):

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_android.cc:18: const char kATraceMarkerFile[] =
"/sys/kernel/trace_event/tracing/trace_marker";
Nope, you got too excited :)
This should stay as it is.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_android.cc:187: // trace_eventfs that takes the
written data and pushes it onto the trace
Revert this.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
File base/trace_event/trace_event_impl.h (right):

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_impl.h:816: using
base::trace_event::ConvertableToTraceFormat;
Nit: order this.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
File base/trace_event/trace_event_impl_constants.cc (right):

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_impl_constants.cc:10: // Enable everything but
trace_event and test categories by default.
Revert this

https://codereview.chromium.org/882673002/diff/1/cc/base/math_util.h
File cc/base/math_util.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/base/math_util.h#newcode28
cc/base/math_util.h:28: namespace debug {
Please add a similar TODO also  to these ones, to highlight that they are
temporary.

https://codereview.chromium.org/882673002/diff/1/cc/quads/draw_quad.h
File cc/quads/draw_quad.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/quads/draw_quad.h#newcode17
cc/quads/draw_quad.h:17: namespace debug {
Nit: add a blankline here

https://codereview.chromium.org/882673002/diff/1/cc/resources/one_copy_tile_t...
File cc/resources/one_copy_tile_task_worker_pool.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/resources/one_copy_tile_t...
cc/resources/one_copy_tile_task_worker_pool.h:22: namespace debug {
Nit: blankline

https://codereview.chromium.org/882673002/diff/1/cc/resources/pixel_buffer_ti...
File cc/resources/pixel_buffer_tile_task_worker_pool.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/resources/pixel_buffer_ti...
cc/resources/pixel_buffer_tile_task_worker_pool.h:23: namespace debug {
nit: blankline

https://codereview.chromium.org/882673002/diff/1/cc/resources/zero_copy_tile_...
File cc/resources/zero_copy_tile_task_worker_pool.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/resources/zero_copy_tile_...
cc/resources/zero_copy_tile_task_worker_pool.h:18: using
::base::trace_event::ConvertableToTraceFormat;
nit: blankline

https://codereview.chromium.org/882673002/diff/1/cc/scheduler/delay_based_tim...
File cc/scheduler/delay_based_time_source.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/scheduler/delay_based_tim...
cc/scheduler/delay_based_time_source.h:20: }
nit: blankline

https://codereview.chromium.org/882673002/diff/1/cc/scheduler/scheduler.h
File cc/scheduler/scheduler.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/scheduler/scheduler.h#new...
cc/scheduler/scheduler.h:32: }
nit: blankline

https://codereview.chromium.org/882673002/diff/1/cc/scheduler/scheduler_setti...
File cc/scheduler/scheduler_settings.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/scheduler/scheduler_setti...
cc/scheduler/scheduler_settings.h:19: }
nit: blankline

https://codereview.chromium.org/882673002/diff/1/cc/scheduler/scheduler_state...
File cc/scheduler/scheduler_state_machine.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/scheduler/scheduler_state...
cc/scheduler/scheduler_state_machine.h:25: using
::base::trace_event::TracedValue;
Nit: blankline

https://codereview.chromium.org/882673002/diff/1/content/browser/browser_main...
File content/browser/browser_main_loop.h (right):

https://codereview.chromium.org/882673002/diff/1/content/browser/browser_main...
content/browser/browser_main_loop.h:30: namespace debug {
Why did you add the trailing comment here and not to the others?

https://codereview.chromium.org/882673002/diff/1/content/browser/browser_main...
content/browser/browser_main_loop.h:31: using
::base::trace_event::TraceMemoryController;
Nit: blankline

https://codereview.chromium.org/882673002/diff/1/content/child/child_thread.h
File content/child/child_thread.h (right):

https://codereview.chromium.org/882673002/diff/1/content/child/child_thread.h...
content/child/child_thread.h:27: namespace debug {
ditto (remove trailing comment)

https://codereview.chromium.org/882673002/diff/1/content/child/child_thread.h...
content/child/child_thread.h:29: }  // namespace debug
nit: blankline

https://codereview.chromium.org/882673002/diff/1/content/renderer/scheduler/t...
File content/renderer/scheduler/task_queue_manager.h (right):

https://codereview.chromium.org/882673002/diff/1/content/renderer/scheduler/t...
content/renderer/scheduler/task_queue_manager.h:24: using
::base::trace_event::ConvertableToTraceFormat;
nit: blankline

https://codereview.chromium.org/882673002/diff/1/content/renderer/scheduler/t...
File content/renderer/scheduler/task_queue_selector.h (right):

https://codereview.chromium.org/882673002/diff/1/content/renderer/scheduler/t...
content/renderer/scheduler/task_queue_selector.h:17: namespace debug {
Double ditto (blankline + trailing comment)

[ssid, 2015-01-27 15:56:46]

Made changes PTAL.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event.h
File base/trace_event/trace_event.h (right):

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event.h:1597: namespace base {
On 2015/01/27 14:34:10, Primiano Tucci wrote:
> Can you please add a TODO(ssid) which a refernce to the bug to explain that
this
> forwarding is temporary to handle the transition gradually?

Done.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
File base/trace_event/trace_event_android.cc (right):

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_android.cc:18: const char kATraceMarkerFile[] =
"/sys/kernel/trace_event/tracing/trace_marker";
On 2015/01/27 14:34:11, Primiano Tucci wrote:
> Nope, you got too excited :)
> This should stay as it is.

Haha, missed this one. Changed.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_android.cc:187: // trace_eventfs that takes the
written data and pushes it onto the trace
On 2015/01/27 14:34:10, Primiano Tucci wrote:
> Revert this.

Done.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
File base/trace_event/trace_event_impl.h (right):

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_impl.h:816: using
base::trace_event::ConvertableToTraceFormat;
On 2015/01/27 14:34:11, Primiano Tucci wrote:
> Nit: order this.

Done.

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
File base/trace_event/trace_event_impl_constants.cc (right):

https://codereview.chromium.org/882673002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_impl_constants.cc:10: // Enable everything but
trace_event and test categories by default.
On 2015/01/27 14:34:11, Primiano Tucci wrote:
> Revert this

Done.

https://codereview.chromium.org/882673002/diff/1/cc/base/math_util.h
File cc/base/math_util.h (right):

https://codereview.chromium.org/882673002/diff/1/cc/base/math_util.h#newcode28
cc/base/math_util.h:28: namespace debug {
On 2015/01/27 14:34:11, Primiano Tucci wrote:
> Please add a similar TODO also  to these ones, to highlight that they are
> temporary.

Done.

[Primiano Tucci (use gerrit), 2015-02-03 10:42:37]

Good work! thanks.

I have just some nits (mostly the format of the TODO message).

Also, I think you should improve and give more context int he CL description. My
proposal would be something as follows (But feel free to change/reword it).


[tracing] move namespace from base::debug to base::trace_event

After having transitioned all the tracing headers from base/debug/ to
base/trace_event, this CL addresses the namespace move.
In principle, this CL should only change the namespace of the
base/trace_event files but the namespace used by the tracing clients.
In order to achieve this, namespace aliases are appended to the
trace_event headers, to make it so that clients can still refer to
base::debug::TraceFoo, with that being aliased to
base::trace_event::TraceFoo.
The upcoming CLs will gradually migrate the clients to use the
base::trace_event namespace and will remove the ns aliases.
Unfortunately, this CL has also to update few tracing clients,
in particular the ones having forward declarations. Forward
declarations, in fact, cannot be aliased as the compiler sees them
before the alias itself.

See crrev.com/837303004 and the related bug for motivations and design doc.

BUG=451032

https://codereview.chromium.org/882673002/diff/80001/base/trace_event/trace_e...
File base/trace_event/trace_event.h (right):

https://codereview.chromium.org/882673002/diff/80001/base/trace_event/trace_e...
base/trace_event/trace_event.h:1597: // This is added temporarily. Once the
renaming of namespace usages
You have some typos in this (and the other comments).
Also, in general the pattern is to refer bugs and not CLs in the TODOs.
My suggestion would be to reword this to be something like:

// TODO(ssid): remove these aliases after the tracing clients are moved to the
// new trace_event namespace. See crbug.com/451032. ETA: March 2015.

https://codereview.chromium.org/882673002/diff/80001/cc/blink/web_layer_impl.h
File cc/blink/web_layer_impl.h (left):

https://codereview.chromium.org/882673002/diff/80001/cc/blink/web_layer_impl....
cc/blink/web_layer_impl.h:32: 
Nit: you accidentally ate this blank line.

https://codereview.chromium.org/882673002/diff/80001/cc/quads/render_pass.h
File cc/quads/render_pass.h (right):

https://codereview.chromium.org/882673002/diff/80001/cc/quads/render_pass.h#n...
cc/quads/render_pass.h:26: 
Nit: I think you want this blank line below "class Value", not above.

https://codereview.chromium.org/882673002/diff/80001/cc/quads/shared_quad_sta...
File cc/quads/shared_quad_state.h (right):

https://codereview.chromium.org/882673002/diff/80001/cc/quads/shared_quad_sta...
cc/quads/shared_quad_state.h:18: 
ditto

[ssid, 2015-02-03 15:08:07]

Made changes.PTAL

https://codereview.chromium.org/882673002/diff/80001/base/trace_event/trace_e...
File base/trace_event/trace_event.h (right):

https://codereview.chromium.org/882673002/diff/80001/base/trace_event/trace_e...
base/trace_event/trace_event.h:1597: // This is added temporarily. Once the
renaming of namespace usages
On 2015/02/03 10:42:36, Primiano Tucci wrote:
> You have some typos in this (and the other comments).
> Also, in general the pattern is to refer bugs and not CLs in the TODOs.
> My suggestion would be to reword this to be something like:
> 
> // TODO(ssid): remove these aliases after the tracing clients are moved to the
> // new trace_event namespace. See crbug.com/451032. ETA: March 2015.

Done.

https://codereview.chromium.org/882673002/diff/80001/cc/blink/web_layer_impl.h
File cc/blink/web_layer_impl.h (left):

https://codereview.chromium.org/882673002/diff/80001/cc/blink/web_layer_impl....
cc/blink/web_layer_impl.h:32: 
On 2015/02/03 10:42:36, Primiano Tucci wrote:
> Nit: you accidentally ate this blank line.

Done.

https://codereview.chromium.org/882673002/diff/80001/cc/quads/render_pass.h
File cc/quads/render_pass.h (right):

https://codereview.chromium.org/882673002/diff/80001/cc/quads/render_pass.h#n...
cc/quads/render_pass.h:26: 
On 2015/02/03 10:42:36, Primiano Tucci wrote:
> Nit: I think you want this blank line below "class Value", not above.

Done.

[Primiano Tucci (use gerrit), 2015-02-03 18:21:56]

primiano@chromium.org changed reviewers:
+ dsinclair@chromium.org

[Primiano Tucci (use gerrit), 2015-02-03 18:21:57]

LGTM thanks. Adding actual owners.
+skyostil for /cc/
+dsinclair for /base/trace_event/

[dsinclair, 2015-02-03 18:25:27]

https://codereview.chromium.org/882673002/diff/100001/cc/scheduler/scheduler.h
File cc/scheduler/scheduler.h (right):

https://codereview.chromium.org/882673002/diff/100001/cc/scheduler/scheduler....
cc/scheduler/scheduler.h:34: using
::base::trace_event::ConvertableToTraceFormat;
Out of curiosity, is it a much larger change to just do the conversion in this
CL instead of adding all the using entries?

[Primiano Tucci (use gerrit), 2015-02-03 18:37:33]

On 2015/02/03 18:25:27, dsinclair wrote:
> https://codereview.chromium.org/882673002/diff/100001/cc/scheduler/scheduler.h
> File cc/scheduler/scheduler.h (right):
> 
>
https://codereview.chromium.org/882673002/diff/100001/cc/scheduler/scheduler....
> cc/scheduler/scheduler.h:34: using
> ::base::trace_event::ConvertableToTraceFormat;
> Out of curiosity, is it a much larger change to just do the conversion in this
> CL instead of adding all the using entries?

The one CL look like:
This CL (without the temporary using aliases) +
crrev.com/879913002 +
crrev.com/892213004 +
crrev.com/868603007 

Which looks kinda big :)
What I can propose is to prepare and get all the four CL reviewed and land them
back to back. 
This means that the forward declarations here will be almost invisible to the
public.

[dsinclair, 2015-02-03 18:40:19]

LGTM.

That's a lot, landing is pieces is cool, I wouldn't worry too much about lining
up all the reviews let's just get them in as we can.

[dsinclair, 2015-02-04 14:34:22]

The CQ bit was checked by dsinclair@chromium.org

[dsinclair, 2015-02-04 14:34:34]

The CQ bit was unchecked by dsinclair@chromium.org

[Primiano Tucci (use gerrit), 2015-02-04 18:23:50]

TBR-ing skyostil for the mechanical changes in cc/ and scheduler/.
I hope you don't mind.
In the contrary case, I sit in slapping distance.

[Primiano Tucci (use gerrit), 2015-02-04 18:23:56]

The CQ bit was checked by primiano@chromium.org

[commit-bot: I haz the power, 2015-02-04 18:24:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/882673002/100001

[commit-bot: I haz the power, 2015-02-04 18:32:14]

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

[commit-bot: I haz the power, 2015-02-04 18:32:16]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Sami, 2015-02-04 18:57:08]

On 2015/02/04 18:23:50, Primiano Tucci wrote:
> TBR-ing skyostil for the mechanical changes in cc/ and scheduler/.
> I hope you don't mind.
> In the contrary case, I sit in slapping distance.

Both lgtm, slapPromise.cancel();

[Sami, 2015-02-04 18:58:13]

Looks like you need to TBR= someone owning content/.

[Primiano Tucci (use gerrit), 2015-02-04 19:59:21]

ssid@, it seems like this needs a rebase. Can you please rebase it (wait for my
LG before carrying on).

[ssid, 2015-02-04 20:25:57]

New patchsets have been uploaded after l-g-t-m from skyostil@chromium.org

[Primiano Tucci (use gerrit), 2015-02-04 22:15:07]

TBR-ing jam for 7 line mechanical diff in content/browser/browser_main_loop.h
and content/child/child_thread_impl.h

[Primiano Tucci (use gerrit), 2015-02-04 22:15:15]

The CQ bit was checked by primiano@chromium.org

[commit-bot: I haz the power, 2015-02-04 22:16:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/882673002/120001

[commit-bot: I haz the power, 2015-02-04 22:20:57]

Committed patchset #7 (id:120001)

[commit-bot: I haz the power, 2015-02-04 22:21:59]

Patchset 7 (id:??) landed as
https://crrev.com/97c5abba36f5ce473cd996fab74fbf5aa9bb5464
Cr-Commit-Position: refs/heads/master@{#314657}

[zhaoqin1, 2015-02-05 03:49:53]

A revert of this CL (patchset #7 id:120001) has been created in
https://codereview.chromium.org/904573002/ by zhaoqin@chromium.org.

The reason for reverting is: broken Memory.FYI TSan bot.
crbug.com/455530.

[Primiano Tucci (use gerrit), 2015-02-05 17:40:24]

On 2015/02/05 03:49:53, zhaoqin1 wrote:
> A revert of this CL (patchset #7 id:120001) has been created in
> https://codereview.chromium.org/904573002/ by mailto:zhaoqin@chromium.org.
> 
> The reason for reverting is: broken Memory.FYI TSan bot.
> crbug.com/455530.

Relanded (with tsan suppressions) in crrev.com/869043008