Extract SourceControl to module; extract common methods to bisect_utils.

Extract SourceControl to module; extract common methods to bisect_utils.

BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285639

[qyearsley, 2014-07-24 20:29:09]

In this CL:

Move the following things to their own module:
  class SourceControl
  class GitSourceControl
  function DetermineAndCreateSourceControl

Move common functions that are used by these and other things in
bisect-perf-regression to the bisect_utils module:
  CheckRunGit
  RunGit
  RunProcess
  RunProcessAndRetrieveOutput
  IsStringInt
  IsStringFloat
  IsWindowsHost
  Is64BitWindows
  IsLinuxHost
  IsMacHost

Since there are no unit tests, I checked whether I had missed anything by just
running pylint on all relevant files until it didn't complain about undefined
variables.

[shatch, 2014-07-25 16:28:50]

lgtm

https://codereview.chromium.org/418113003/diff/1/tools/auto_bisect/source_con...
File tools/auto_bisect/source_control.py (right):

https://codereview.chromium.org/418113003/diff/1/tools/auto_bisect/source_con...
tools/auto_bisect/source_control.py:30: class SourceControl(object):
Not for this CL, but probably ok to kill the abstraction in the future, since
everything is git based now (and we never actually implemented svn support
anyway).

[prasadv, 2014-07-25 17:40:25]

lgtm

[qyearsley, 2014-07-25 17:44:51]

The CQ bit was checked by qyearsley@chromium.org

[commit-bot: I haz the power, 2014-07-25 17:46:38]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/qyearsley@chromium.org/418113003/1

[commit-bot: I haz the power, 2014-07-25 19:03:50]

Change committed as 285639