[DO NOT LAND] Add some scripts to diagnose impact of crbug.com/684270.

[DO NOT LAND] Add some scripts to diagnose impact of crbug.com/684270.

Includes dpranke's script from crrev.com/2660133002 and adds some new
scripts which diagnose the OWNERS coverage in different ways.

rietveld_source_owners.py is the current complete script, which:
- Identifies which CLs contain one or more "non-source" files[1].
- For each affected CL, checks out the preceding revision to allow
  OWNERS to be correctly checked against.
- For each CL with one or more files missing OWNERS (i.e. neither the
  author, nor any approver, nor any TBR, applies to the file) collates
  the affected files by type (usually based on extension).

BUG=684270

[Wez, 2017-02-06 22:14:19]

wez@chromium.org changed reviewers:
+ dcheng@chromium.org, dpranke@chromium.org

[Wez, 2017-02-06 22:14:20]

FYI, chaps.

[Wez, 2017-02-07 01:35:13]

Wibble

[Wez, 2017-02-07 01:35:21]

Wibble\nBibble

[Wez, 2017-02-07 01:48:35]

Wibble
Bibble

[Wez, 2017-02-08 18:02:20]

Marking this closed to get it out of my code review queue. ;)

[Wez, 2017-02-08 18:31:39]

Description was changed from

==========
[DO NOT LAND] Add some scripts to diagnose impact of crbug.com/684270.

Includes dpranke's script from crrev.com/2660133002 and adds some new
scripts which diagnose the OWNERS coverage in different ways.

rietveld_source_owners.py is the current complete script, which:
- Identifies which CLs contain one or more "non-source" files[1].
- For each affected CL, checks out the preceding revision to allow
  OWNERS to be correctly checked against.
- For each CL with one or more files missing OWNERS (i.e. neither the
  author, nor any approver, nor any TBR, applies to the file) collates
  the affected files by type (usually based on extension).

BUG=684270
==========

to

==========
[DO NOT LAND] Add some scripts to diagnose impact of crbug.com/684270.

Includes dpranke's script from crrev.com/2660133002 and adds some new
scripts which diagnose the OWNERS coverage in different ways.

rietveld_source_owners.py is the current complete script, which:
- Identifies which CLs contain one or more "non-source" files[1].
- For each affected CL, checks out the preceding revision to allow
  OWNERS to be correctly checked against.
- For each CL with one or more files missing OWNERS (i.e. neither the
  author, nor any approver, nor any TBR, applies to the file) collates
  the affected files by type (usually based on extension).

BUG=684270
==========