Revert of Optimize check_gn_headers.py for speed

Revert of Optimize check_gn_headers.py for speed (patchset #1 id:1 of https://codereview.chromium.org/2842513003/ )

Reason for revert:
This optimization was buggy and broke the ninja parsing.

Original issue's description:
> Optimize check_gn_headers.py for speed
> 
> Process the output of 'ninja' live through the pipe rather than waiting
> for it to finish.
> 
> Before:
> 20.74user 16.36system 0:24.57elapsed 151%CPU
> 
> After:
> 16.63user 9.24system 0:13.94elapsed 185%CPU
> 
> BUG=661774
> 
> Review-Url: https://codereview.chromium.org/2842513003
> Cr-Commit-Position: refs/heads/master@{#466900}
> Committed: https://chromium.googlesource.com/chromium/src/+/6b609383cf3669b0670b567249ff868ea4b26e43

TBR=dpranke@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=661774
Review-Url: https://codereview.chromium.org/2844623002
Cr-Commit-Position: refs/heads/master@{#467231}
Committed: https://chromium.googlesource.com/chromium/src/+/c219b8a1823f884703c3546bf2cb7c17fb737d67

[wychen, 2017-04-26 04:09:00]

The CQ bit was checked by wychen@chromium.org

[wychen, 2017-04-26 04:09:00]

Created Revert of Optimize check_gn_headers.py for speed

[commit-bot: I haz the power, 2017-04-26 04:09:23]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-26 04:09:49]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493179740490550, "parent_rev":
"74946c37525c8b29f9b7b117c2d092a31b467b4d", "commit_rev":
"c219b8a1823f884703c3546bf2cb7c17fb737d67"}

[commit-bot: I haz the power, 2017-04-26 04:10:39]

Description was changed from

==========
Revert of Optimize check_gn_headers.py for speed (patchset #1 id:1 of
https://codereview.chromium.org/2842513003/ )

Reason for revert:
This optimization was buggy and broke the ninja parsing.

Original issue's description:
> Optimize check_gn_headers.py for speed
> 
> Process the output of 'ninja' live through the pipe rather than waiting
> for it to finish.
> 
> Before:
> 20.74user 16.36system 0:24.57elapsed 151%CPU
> 
> After:
> 16.63user 9.24system 0:13.94elapsed 185%CPU
> 
> BUG=661774
> 
> Review-Url: https://codereview.chromium.org/2842513003
> Cr-Commit-Position: refs/heads/master@{#466900}
> Committed:
https://chromium.googlesource.com/chromium/src/+/6b609383cf3669b0670b567249ff...

TBR=dpranke@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=661774
==========

to

==========
Revert of Optimize check_gn_headers.py for speed (patchset #1 id:1 of
https://codereview.chromium.org/2842513003/ )

Reason for revert:
This optimization was buggy and broke the ninja parsing.

Original issue's description:
> Optimize check_gn_headers.py for speed
> 
> Process the output of 'ninja' live through the pipe rather than waiting
> for it to finish.
> 
> Before:
> 20.74user 16.36system 0:24.57elapsed 151%CPU
> 
> After:
> 16.63user 9.24system 0:13.94elapsed 185%CPU
> 
> BUG=661774
> 
> Review-Url: https://codereview.chromium.org/2842513003
> Cr-Commit-Position: refs/heads/master@{#466900}
> Committed:
https://chromium.googlesource.com/chromium/src/+/6b609383cf3669b0670b567249ff...

TBR=dpranke@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=661774

Review-Url: https://codereview.chromium.org/2844623002
Cr-Commit-Position: refs/heads/master@{#467231}
Committed:
https://chromium.googlesource.com/chromium/src/+/c219b8a1823f884703c3546bf2cb...
==========

[commit-bot: I haz the power, 2017-04-26 04:10:41]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/c219b8a1823f884703c3546bf2cb...

[Dirk Pranke, 2017-04-26 04:29:40]

lgtm

[wychen, 2017-04-26 04:30:30]

On 2017/04/26 04:29:40, Dirk Pranke wrote:
> lgtm

Sorry, should've double checked when cherry-picking from an ancient local
branch.