Revert of Add helpful error messages to check_gn_headers.py

Revert of Add helpful error messages to check_gn_headers.py (patchset #3 id:40001 of https://codereview.chromium.org/2891363004/ )

Reason for revert:
This CL is likely causing massive failures:

https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder/builds/84473
to
https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder/builds/84498

and 

https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder%20%28dbg%29/builds/111528
to
https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder%20%28dbg%29/builds/111542

Original issue's description:
> Add helpful error messages to check_gn_headers.py
> 
> Before running check_gn_headers.py, it is necessary to build all
> in order to get the dependency info from the compiler. Directly
> checking whether rebuilding is needed by running a build dry run
> takes too long, so some heuristics are used instead.
> 
> BUG=661774
> 
> Review-Url: https://codereview.chromium.org/2891363004
> Cr-Commit-Position: refs/heads/master@{#474588}
> Committed: https://chromium.googlesource.com/chromium/src/+/0ceaba5ef538ce1780578d5e948641bc27f5829b

TBR=dpranke@chromium.org,tfarina@chromium.org,wychen@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/2905863002
Cr-Commit-Position: refs/heads/master@{#474649}
Committed: https://chromium.googlesource.com/chromium/src/+/d3c2681426db53550547f2bc115c3f72ba40f276

[Moe, 2017-05-25 14:51:22]

The CQ bit was checked by mahmadi@chromium.org

[Moe, 2017-05-25 14:51:22]

Created Revert of Add helpful error messages to check_gn_headers.py

[commit-bot: I haz the power, 2017-05-25 14:51:42]

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, 2017-05-25 14:52:05]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1495723882396660, "parent_rev":
"7451dfbdb556c67f808234f6ec9a76df1a259b18", "commit_rev":
"d3c2681426db53550547f2bc115c3f72ba40f276"}

[commit-bot: I haz the power, 2017-05-25 14:52:17]

Description was changed from

==========
Revert of Add helpful error messages to check_gn_headers.py (patchset #3
id:40001 of https://codereview.chromium.org/2891363004/ )

Reason for revert:
This CL is likely causing massive failures:

https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder/builds/8...
to
https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder/builds/8...

and 

https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder%20%28dbg...
to
https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder%20%28dbg...

Original issue's description:
> Add helpful error messages to check_gn_headers.py
> 
> Before running check_gn_headers.py, it is necessary to build all
> in order to get the dependency info from the compiler. Directly
> checking whether rebuilding is needed by running a build dry run
> takes too long, so some heuristics are used instead.
> 
> BUG=661774
> 
> Review-Url: https://codereview.chromium.org/2891363004
> Cr-Commit-Position: refs/heads/master@{#474588}
> Committed:
https://chromium.googlesource.com/chromium/src/+/0ceaba5ef538ce1780578d5e9486...

TBR=dpranke@chromium.org,tfarina@chromium.org,wychen@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 Add helpful error messages to check_gn_headers.py (patchset #3
id:40001 of https://codereview.chromium.org/2891363004/ )

Reason for revert:
This CL is likely causing massive failures:

https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder/builds/8...
to
https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder/builds/8...

and 

https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder%20%28dbg...
to
https://build.chromium.org/p/chromium.linux/builders/Linux%20Builder%20%28dbg...

Original issue's description:
> Add helpful error messages to check_gn_headers.py
> 
> Before running check_gn_headers.py, it is necessary to build all
> in order to get the dependency info from the compiler. Directly
> checking whether rebuilding is needed by running a build dry run
> takes too long, so some heuristics are used instead.
> 
> BUG=661774
> 
> Review-Url: https://codereview.chromium.org/2891363004
> Cr-Commit-Position: refs/heads/master@{#474588}
> Committed:
https://chromium.googlesource.com/chromium/src/+/0ceaba5ef538ce1780578d5e9486...

TBR=dpranke@chromium.org,tfarina@chromium.org,wychen@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/2905863002
Cr-Commit-Position: refs/heads/master@{#474649}
Committed:
https://chromium.googlesource.com/chromium/src/+/d3c2681426db53550547f2bc115c...
==========

[commit-bot: I haz the power, 2017-05-25 14:52:21]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/d3c2681426db53550547f2bc115c...

[Dirk Pranke, 2017-05-25 16:12:16]

lgtm

[wychen, 2017-05-25 20:36:00]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2907683002/ by wychen@chromium.org.

The reason for reverting is: The real culprit is https://crrev.com/2903733004/,
which was reverted.
This CL (https://crrev.com/2891363004) made it fail more gracefully, and should
be kept..