Revert of Simplify the initialization of Git objects in Host.

Revert of Simplify the initialization of Git objects in Host. (patchset #3 id:40001 of https://codereview.chromium.org/2663623003/ )

Reason for revert:
Speculative revert. This might be the cause of build flakiness, see crbug.com/687707

Original issue's description:
> Simplify the initialization of Git objects in Host.
> 
> This CL makes calling Host.initialize_scm() unnecessary by making
> it so that the Git object is initialized when required. It also
> merges scm() and scm_for_path(), and moves initialization logic
> into the Git class.
> 
> BUG=676012
> 
> Review-Url: https://codereview.chromium.org/2663623003
> Cr-Commit-Position: refs/heads/master@{#447582}
> Committed: https://chromium.googlesource.com/chromium/src/+/7091f37e5b763d57e4752a4e69cf46719b8ea1c4

TBR=jeffcarp@chromium.org,qyearsley@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=676012
Review-Url: https://codereview.chromium.org/2671583002
Cr-Commit-Position: refs/heads/master@{#447650}
Committed: https://chromium.googlesource.com/chromium/src/+/6cd1e0590f82ef11669abfbf00d846d759235460

[lushnikov, 2017-02-02 00:08:23]

The CQ bit was checked by lushnikov@chromium.org

[lushnikov, 2017-02-02 00:08:23]

Created Revert of Simplify the initialization of Git objects in Host.

[commit-bot: I haz the power, 2017-02-02 00:08:58]

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, 2017-02-02 00:09:49]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1485994103114870, "parent_rev":
"a3d5801d55db75ed92b135170b561f2eab7761f3", "commit_rev":
"6cd1e0590f82ef11669abfbf00d846d759235460"}

[commit-bot: I haz the power, 2017-02-02 00:10:25]

Description was changed from

==========
Revert of Simplify the initialization of Git objects in Host. (patchset #3
id:40001 of https://codereview.chromium.org/2663623003/ )

Reason for revert:
Speculative revert. This might be the cause of build flakiness, see
crbug.com/687707

Original issue's description:
> Simplify the initialization of Git objects in Host.
> 
> This CL makes calling Host.initialize_scm() unnecessary by making
> it so that the Git object is initialized when required. It also
> merges scm() and scm_for_path(), and moves initialization logic
> into the Git class.
> 
> BUG=676012
> 
> Review-Url: https://codereview.chromium.org/2663623003
> Cr-Commit-Position: refs/heads/master@{#447582}
> Committed:
https://chromium.googlesource.com/chromium/src/+/7091f37e5b763d57e4752a4e69cf...

TBR=jeffcarp@chromium.org,qyearsley@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=676012
==========

to

==========
Revert of Simplify the initialization of Git objects in Host. (patchset #3
id:40001 of https://codereview.chromium.org/2663623003/ )

Reason for revert:
Speculative revert. This might be the cause of build flakiness, see
crbug.com/687707

Original issue's description:
> Simplify the initialization of Git objects in Host.
> 
> This CL makes calling Host.initialize_scm() unnecessary by making
> it so that the Git object is initialized when required. It also
> merges scm() and scm_for_path(), and moves initialization logic
> into the Git class.
> 
> BUG=676012
> 
> Review-Url: https://codereview.chromium.org/2663623003
> Cr-Commit-Position: refs/heads/master@{#447582}
> Committed:
https://chromium.googlesource.com/chromium/src/+/7091f37e5b763d57e4752a4e69cf...

TBR=jeffcarp@chromium.org,qyearsley@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=676012

Review-Url: https://codereview.chromium.org/2671583002
Cr-Commit-Position: refs/heads/master@{#447650}
Committed:
https://chromium.googlesource.com/chromium/src/+/6cd1e0590f82ef11669abfbf00d8...
==========

[commit-bot: I haz the power, 2017-02-02 00:10:26]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/6cd1e0590f82ef11669abfbf00d8...

[qyearsley, 2017-02-04 02:02:10]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2676673006/ by qyearsley@chromium.org.

The reason for reverting is: Reverting speculative revert; the flaky failure on
Mac was unrelated to this CL..