ServiceManager: Simplify Instance lifetime management

ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow. Root instances are now explicitly owned by the
ServiceManager and non-root instances are explicitly owned by
their parent Instance.

OnInstanceError always destroys the Instance, either by
removing it from the root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter their
parent on destruction.

Notification logic has been extracted from OnInstanceError and
moved to a new OnInstanceStopped, which is always called by
each Instance's destructor. This allows parents to delete their
own children without calling through to OnInstanceError, while
still allowing the ServiceManager to know about the destruction
and dispatch notifications accordingly.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
Committed: https://crrev.com/262a9e00334328804c7515ba4e2f840aee8ec681
Cr-Commit-Position: refs/heads/master@{#418643}

[Ken Rockot(use gerrit already), 2016-09-14 18:26:22]

Description was changed from

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow.

Root instances are explicitly owned by the ServiceManager.
Non-root instances are explicitly owned by their parent
Instance.

OnInstanceError always destroys the Instance and is the only
valid way to destroy an instance. It does so either by
removing from root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter
their parent on destruction.

OnInstanceStopped has been extracted from OnInstanceError
and is now called by all Instance destructors.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable.

BUG=640488
==========

to

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow.

Root instances are explicitly owned by the ServiceManager.
Non-root instances are explicitly owned by their parent
Instance.

OnInstanceError always destroys the Instance and is the only
valid way to destroy an instance. It does so either by
removing from root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter
their parent on destruction.

OnInstanceStopped has been extracted from OnInstanceError
and is now called by all Instance destructors.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
==========

[Ken Rockot(use gerrit already), 2016-09-14 18:26:27]

The CQ bit was checked by rockot@chromium.org to run a CQ dry run

[Ken Rockot(use gerrit already), 2016-09-14 18:26:38]

rockot@chromium.org changed reviewers:
+ ben@chromium.org

[commit-bot: I haz the power, 2016-09-14 18:27:15]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Ken Rockot(use gerrit already), 2016-09-14 18:29:18]

The CQ bit was checked by rockot@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-09-14 18:29:22]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Ken Rockot(use gerrit already), 2016-09-14 19:09:45]

Description was changed from

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow.

Root instances are explicitly owned by the ServiceManager.
Non-root instances are explicitly owned by their parent
Instance.

OnInstanceError always destroys the Instance and is the only
valid way to destroy an instance. It does so either by
removing from root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter
their parent on destruction.

OnInstanceStopped has been extracted from OnInstanceError
and is now called by all Instance destructors.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
==========

to

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow.

Root instances are explicitly owned by the ServiceManager.
Non-root instances are explicitly owned by their parent
Instance.

OnInstanceError always destroys the Instance and is the only
valid way to destroy an instance. It does so either by
removing from the root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter
their parent on destruction.

OnInstanceStopped has been extracted from OnInstanceError
and is now called by all Instance destructors.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
==========

[Ken Rockot(use gerrit already), 2016-09-14 19:10:33]

Description was changed from

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow.

Root instances are explicitly owned by the ServiceManager.
Non-root instances are explicitly owned by their parent
Instance.

OnInstanceError always destroys the Instance and is the only
valid way to destroy an instance. It does so either by
removing from the root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter
their parent on destruction.

OnInstanceStopped has been extracted from OnInstanceError
and is now called by all Instance destructors.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
==========

to

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow.

Root instances are explicitly owned by the ServiceManager.
Non-root instances are explicitly owned by their parent
Instance.

OnInstanceError always destroys the Instance and is the only
valid way to destroy an instance. It does so either by
removing from the root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter
their parent on destruction.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
==========

[Ken Rockot(use gerrit already), 2016-09-14 19:20:44]

Description was changed from

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow.

Root instances are explicitly owned by the ServiceManager.
Non-root instances are explicitly owned by their parent
Instance.

OnInstanceError always destroys the Instance and is the only
valid way to destroy an instance. It does so either by
removing from the root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter
their parent on destruction.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
==========

to

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow. Root instances are now explicitly owned by the
ServiceManager and non-root instances are explicitly owned by
their parent Instance.

OnInstanceError always destroys the Instance, either by
removing it from the root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter their
parent on destruction.

Notification logic has been extracted from OnInstanceError and
moved to a new OnInstanceStopped, which is always called by
each Instance's destructor. This allows parents to delete their
own children without calling through to OnInstanceError, while
still allowing the ServiceManager to know about the destruction
and dispatch notifications accordingly.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
==========

[Ben Goodger (Google), 2016-09-14 19:31:21]

lgtm

[Ken Rockot(use gerrit already), 2016-09-14 19:33:10]

The CQ bit was unchecked by rockot@chromium.org

[Ken Rockot(use gerrit already), 2016-09-14 19:33:11]

The CQ bit was checked by rockot@chromium.org

[commit-bot: I haz the power, 2016-09-14 19:33:33]

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, 2016-09-14 19:39:57]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-09-14 19:42:07]

Description was changed from

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow. Root instances are now explicitly owned by the
ServiceManager and non-root instances are explicitly owned by
their parent Instance.

OnInstanceError always destroys the Instance, either by
removing it from the root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter their
parent on destruction.

Notification logic has been extracted from OnInstanceError and
moved to a new OnInstanceStopped, which is always called by
each Instance's destructor. This allows parents to delete their
own children without calling through to OnInstanceError, while
still allowing the ServiceManager to know about the destruction
and dispatch notifications accordingly.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488
==========

to

==========
ServiceManager: Simplify Instance lifetime management

Makes Instance ownership and lifetime management easier to
follow. Root instances are now explicitly owned by the
ServiceManager and non-root instances are explicitly owned by
their parent Instance.

OnInstanceError always destroys the Instance, either by
removing it from the root instance set or delegating to the parent
Instance. This avoids the need for children to re-enter their
parent on destruction.

Notification logic has been extracted from OnInstanceError and
moved to a new OnInstanceStopped, which is always called by
each Instance's destructor. This allows parents to delete their
own children without calling through to OnInstanceError, while
still allowing the ServiceManager to know about the destruction
and dispatch notifications accordingly.

InstanceErrorType is removed: if an Instance becomes
unreachable it's simply removed from the identity map
via a new OnInstanceUnreachable call.

BUG=640488

Committed: https://crrev.com/262a9e00334328804c7515ba4e2f840aee8ec681
Cr-Commit-Position: refs/heads/master@{#418643}
==========

[commit-bot: I haz the power, 2016-09-14 19:42:08]

Patchset 2 (id:??) landed as
https://crrev.com/262a9e00334328804c7515ba4e2f840aee8ec681
Cr-Commit-Position: refs/heads/master@{#418643}