Decouple EventWithLatencyInfo and WebInputEventTraits [extern templates]

Decouple EventWithLatencyInfo and WebInputEventTraits

Only EventWithLatencyInfo uses [Can]Coalesce() from WebInputEventTraits.
WebInputEventTraits gets used for IPC stuff so is kinda sensitive, but
EventWithLatencyInfo isn't involved with IPC. So, coupling these
together also makes refactoring unnecessarily difficult.

E.g. the coupling means that if we want to move EventWithLatencyInfo to
a component, then WebInputEventTraits and a bunch of dependencies that
EventWithLatencyInfo doesn't care about need to come as well.

To decouple, the guts of [Can]Coalesce() moves to a new .cc file for
EventWithLatencyInfo. The types are known, so we get some added type
safety versus WebInputEventTraits which isn't templatized in the .h (the
instantiations in the .cc also become a bit simpler).

To allow the guts to be hidden, use extern templates. This also takes
some burden off the compiler/linker since less code needs to be
generated on the fly and collapsed at link time.

BUG=623844, 615948

[tapted, 2016-06-24 03:01:40]

Description was changed from

==========
Decouple EventWithLatencyInfo and WebInputEventTraits

Only EventWithLatencyInfo uses [Can]Coalesce() from WebInputEventTraits.
WebInputEventTraits gets used for IPC stuff so is kinda sensitive, but
EventWithLatencyInfo isn't involved with IPC.

The coupling also means that if we want to move EventWithLatencyInfo to
a component WebInputEventTraits and a bunch of dependencies that
EventWithLatencyInfo doesn't care about need to come as well.

To decouple, the guts of [Can]Coalesce() moves to a new .cc file for
EventWithLatencyInfo. The types are known, so we get some added type
safety versus WebInputEventTraits which isn't templatized in the .h
(the instantiations in the .cc also become a bit simpler).

To allow the guts to be hidden, use extern templates. This also takes
some burden off the compiler/linker since less code needs to be generated.

BUG=615948
==========

to

==========
Decouple EventWithLatencyInfo and WebInputEventTraits

Only EventWithLatencyInfo uses [Can]Coalesce() from WebInputEventTraits.
WebInputEventTraits gets used for IPC stuff so is kinda sensitive, but
EventWithLatencyInfo isn't involved with IPC.

The coupling also means that if we want to move EventWithLatencyInfo to
a component, then WebInputEventTraits and a bunch of dependencies that
EventWithLatencyInfo doesn't care about need to come as well.

To decouple, the guts of [Can]Coalesce() moves to a new .cc file for
EventWithLatencyInfo. The types are known, so we get some added type
safety versus WebInputEventTraits which isn't templatized in the .h (the
instantiations in the .cc also become a bit simpler).

To allow the guts to be hidden, use extern templates. This also takes
some burden off the compiler/linker since less code needs to be
generated on the fly and collapsed at link time.

BUG=615948
==========

[tapted, 2016-06-24 03:01:40]

tapted@chromium.org changed reviewers:
+ tdresser@chromium.org

[tapted, 2016-06-28 00:35:19]

Patchset #11 (id:200001) has been deleted

[tapted, 2016-06-28 03:30:23]

Description was changed from

==========
Decouple EventWithLatencyInfo and WebInputEventTraits

Only EventWithLatencyInfo uses [Can]Coalesce() from WebInputEventTraits.
WebInputEventTraits gets used for IPC stuff so is kinda sensitive, but
EventWithLatencyInfo isn't involved with IPC.

The coupling also means that if we want to move EventWithLatencyInfo to
a component, then WebInputEventTraits and a bunch of dependencies that
EventWithLatencyInfo doesn't care about need to come as well.

To decouple, the guts of [Can]Coalesce() moves to a new .cc file for
EventWithLatencyInfo. The types are known, so we get some added type
safety versus WebInputEventTraits which isn't templatized in the .h (the
instantiations in the .cc also become a bit simpler).

To allow the guts to be hidden, use extern templates. This also takes
some burden off the compiler/linker since less code needs to be
generated on the fly and collapsed at link time.

BUG=615948
==========

to

==========
Decouple EventWithLatencyInfo and WebInputEventTraits

Only EventWithLatencyInfo uses [Can]Coalesce() from WebInputEventTraits.
WebInputEventTraits gets used for IPC stuff so is kinda sensitive, but
EventWithLatencyInfo isn't involved with IPC. So, coupling these
together also makes refactoring unnecessarily difficult.

E.g. the coupling means that if we want to move EventWithLatencyInfo to
a component, then WebInputEventTraits and a bunch of dependencies that
EventWithLatencyInfo doesn't care about need to come as well.

To decouple, the guts of [Can]Coalesce() moves to a new .cc file for
EventWithLatencyInfo. The types are known, so we get some added type
safety versus WebInputEventTraits which isn't templatized in the .h (the
instantiations in the .cc also become a bit simpler).

To allow the guts to be hidden, use extern templates. This also takes
some burden off the compiler/linker since less code needs to be
generated on the fly and collapsed at link time.

BUG=615948
==========

[tapted, 2016-06-30 05:19:35]

tapted@chromium.org changed reviewers:
- tdresser@chromium.org

[tapted, 2016-11-03 02:00:44]

Description was changed from

==========
Decouple EventWithLatencyInfo and WebInputEventTraits

Only EventWithLatencyInfo uses [Can]Coalesce() from WebInputEventTraits.
WebInputEventTraits gets used for IPC stuff so is kinda sensitive, but
EventWithLatencyInfo isn't involved with IPC. So, coupling these
together also makes refactoring unnecessarily difficult.

E.g. the coupling means that if we want to move EventWithLatencyInfo to
a component, then WebInputEventTraits and a bunch of dependencies that
EventWithLatencyInfo doesn't care about need to come as well.

To decouple, the guts of [Can]Coalesce() moves to a new .cc file for
EventWithLatencyInfo. The types are known, so we get some added type
safety versus WebInputEventTraits which isn't templatized in the .h (the
instantiations in the .cc also become a bit simpler).

To allow the guts to be hidden, use extern templates. This also takes
some burden off the compiler/linker since less code needs to be
generated on the fly and collapsed at link time.

BUG=615948
==========

to

==========
Decouple EventWithLatencyInfo and WebInputEventTraits

Only EventWithLatencyInfo uses [Can]Coalesce() from WebInputEventTraits.
WebInputEventTraits gets used for IPC stuff so is kinda sensitive, but
EventWithLatencyInfo isn't involved with IPC. So, coupling these
together also makes refactoring unnecessarily difficult.

E.g. the coupling means that if we want to move EventWithLatencyInfo to
a component, then WebInputEventTraits and a bunch of dependencies that
EventWithLatencyInfo doesn't care about need to come as well.

To decouple, the guts of [Can]Coalesce() moves to a new .cc file for
EventWithLatencyInfo. The types are known, so we get some added type
safety versus WebInputEventTraits which isn't templatized in the .h (the
instantiations in the .cc also become a bit simpler).

To allow the guts to be hidden, use extern templates. This also takes
some burden off the compiler/linker since less code needs to be
generated on the fly and collapsed at link time.

BUG=623844,615948
==========