Revert 255357 "Change the user action file format from .txt to ...."

Revert 255357 "Change the user action file format from .txt to ...."

Believed to be behind the failures in the Linux builder:

http://build.chromium.org/p/chromium/builders/Linux/builds/47996

Errors in the log:

.../actions/print_style.py: Has executable bit but not shebang or ELF header
.../histograms/print_style.py: Has executable bit but not shebang or ELF header

Refers to files in the CL.

> Change the user action file format from .txt to .xml.
>
> In this way, more information can be added (currently added 'description' and 'owner' for each action)
>
> A few functions are moved from tools/metrics/histograms to tools/metrics/common to be shared by tools/metrics and tools/histograms.
>
> BUG=340735
> NOTRY=true
>
> Review URL: https://codereview.chromium.org/149503005

TBR=yiyaoliu@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=255404

[dcaiafa, 2014-03-06 18:55:46]

Committed patchset #1 manually as r255404 (tree was closed).