Allow stepping into Object.observe handlers.

Allow stepping into Object.observe handlers.

BUG=chromium:432468
R=yangguo@chromium.org, adamk@chromium.org
LOG=N

Committed: https://chromium.googlesource.com/v8/v8/+/fdcfc6a689c3d256600b18cbf47f1675b83db1ab

[Yang, 2014-11-18 11:46:39]

https://codereview.chromium.org/739523002/diff/1/src/debug.h
File src/debug.h (right):

https://codereview.chromium.org/739523002/diff/1/src/debug.h#newcode413
src/debug.h:413: StepAction LastStepAction() { return
thread_local_.last_step_action_; }
I'm curious why StepInActive is no longer sufficient. Did anything break?

[aandrey, 2014-11-18 11:52:24]

https://codereview.chromium.org/739523002/diff/1/src/debug.h
File src/debug.h (right):

https://codereview.chromium.org/739523002/diff/1/src/debug.h#newcode413
src/debug.h:413: StepAction LastStepAction() { return
thread_local_.last_step_action_; }
On 2014/11/18 11:46:39, Yang wrote:
> I'm curious why StepInActive is no longer sufficient. Did anything break?

A StepIn action may not necessarily lead to StepInActive() being true. e.g. a
StepIn may actually result in calling ActivateStepOut() instead.

In this patch we "promote" StepIn to also step into microtasks (and/or across
js->c++->js boundaries).
Otherwise, there is no way to step into Promise/O.o callbacks other than setting
a breakpoint.

[aandrey, 2014-11-18 11:54:42]

On 2014/11/18 11:52:24, aandrey wrote:
> https://codereview.chromium.org/739523002/diff/1/src/debug.h
> File src/debug.h (right):
> 
> https://codereview.chromium.org/739523002/diff/1/src/debug.h#newcode413
> src/debug.h:413: StepAction LastStepAction() { return
> thread_local_.last_step_action_; }
> On 2014/11/18 11:46:39, Yang wrote:
> > I'm curious why StepInActive is no longer sufficient. Did anything break?
> 
> A StepIn action may not necessarily lead to StepInActive() being true. e.g. a
> StepIn may actually result in calling ActivateStepOut() instead.
> 
> In this patch we "promote" StepIn to also step into microtasks (and/or across
> js->c++->js boundaries).
> Otherwise, there is no way to step into Promise/O.o callbacks other than
setting
> a breakpoint.

Similar effort to promise StepInto across Blink task boundaries:
https://codereview.chromium.org/732593002/

[aandrey, 2014-11-18 16:07:44]

https://codereview.chromium.org/739523002/diff/20001/src/debug.h
File src/debug.h (right):

https://codereview.chromium.org/739523002/diff/20001/src/debug.h#newcode413
src/debug.h:413: StepAction LastStepAction() { return
thread_local_.last_step_action_; }
or should I name it last_step_action()?

[Yang, 2014-11-18 16:11:19]

On 2014/11/18 16:07:44, aandrey wrote:
> https://codereview.chromium.org/739523002/diff/20001/src/debug.h
> File src/debug.h (right):
> 
> https://codereview.chromium.org/739523002/diff/20001/src/debug.h#newcode413
> src/debug.h:413: StepAction LastStepAction() { return
> thread_local_.last_step_action_; }
> or should I name it last_step_action()?

I think I'd prefer that.

[aandrey, 2014-11-18 16:20:42]

On 2014/11/18 16:11:19, Yang wrote:
> On 2014/11/18 16:07:44, aandrey wrote:
> > https://codereview.chromium.org/739523002/diff/20001/src/debug.h
> > File src/debug.h (right):
> > 
> > https://codereview.chromium.org/739523002/diff/20001/src/debug.h#newcode413
> > src/debug.h:413: StepAction LastStepAction() { return
> > thread_local_.last_step_action_; }
> > or should I name it last_step_action()?
> 
> I think I'd prefer that.

Done.

[aandrey, 2014-11-19 10:54:06]

Added test/mjsunit/debug-stepin-foreach.js

PTAL.

[Yang, 2014-11-19 14:05:58]

On 2014/11/19 10:54:06, aandrey wrote:
> Added test/mjsunit/debug-stepin-foreach.js
> 
> PTAL.

LGTM. Please run blink's inspector tests before landing this.

[aandrey, 2014-11-19 14:49:20]

The CQ bit was checked by aandrey@chromium.org

[commit-bot: I haz the power, 2014-11-19 14:49:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/739523002/80001

[commit-bot: I haz the power, 2014-11-19 15:16:37]

Committed patchset #5 (id:80001)