Make ui::InputDeviceEventObserver provide a default implementation

Make ui::InputDeviceEventObserver provide a default implementation

BUG=None
TEST=None
R=sadrul
TBR=oshima (For trivial removing of empty implementations in classes which implement InputDeviceEventObserver)

Committed: https://crrev.com/3a50bbb3427ce20ad60bc2966358081b529de76d
Cr-Commit-Position: refs/heads/master@{#317908}

[pkotwicz, 2015-02-20 19:31:31]

pkotwicz@chromium.org changed reviewers:
+ sadrul@chromium.org

[pkotwicz, 2015-02-20 19:31:32]

Sadrul, PTAL. I think this was one of your requests in
https://codereview.chromium.org/889403003

[sadrul, 2015-02-20 20:12:27]

https://codereview.chromium.org/945983002/diff/1/ui/events/devices/input_devi...
File ui/events/devices/input_device_event_observer.h (right):

https://codereview.chromium.org/945983002/diff/1/ui/events/devices/input_devi...
ui/events/devices/input_device_event_observer.h:21: virtual
~InputDeviceEventObserver() {}
I think this should remain public. Maybe make the default ctor protected
instead?

[sadrul, 2015-02-20 20:12:44]

Also, thanks!

[pkotwicz, 2015-02-20 21:22:50]

https://codereview.chromium.org/945983002/diff/1/ui/events/devices/input_devi...
File ui/events/devices/input_device_event_observer.h (right):

https://codereview.chromium.org/945983002/diff/1/ui/events/devices/input_devi...
ui/events/devices/input_device_event_observer.h:21: virtual
~InputDeviceEventObserver() {}
Ok, I've made the destructor public!

We seem to make the destructor protected in some cases. WidgetObserver,
ShellObserver and EnvObserver do this. Is there a reason for the preference in
whether the destructor should be public/protected

[sadrul, 2015-02-23 17:02:53]

lgtm

https://codereview.chromium.org/945983002/diff/1/ui/events/devices/input_devi...
File ui/events/devices/input_device_event_observer.h (right):

https://codereview.chromium.org/945983002/diff/1/ui/events/devices/input_devi...
ui/events/devices/input_device_event_observer.h:21: virtual
~InputDeviceEventObserver() {}
On 2015/02/20 21:22:50, pkotwicz wrote:
> Ok, I've made the destructor public!
> 
> We seem to make the destructor protected in some cases. WidgetObserver,
> ShellObserver and EnvObserver do this. Is there a reason for the preference in
> whether the destructor should be public/protected

I think the point of making the dtor protected is to disallow creating this
observer (because it doesn't do anything by itself). But this can also prevent
someone from doing scoped_ptr<Observer> obs(new
SomeImplementationOfObserver(...));. So instead, the better way would be to make
the ctor protected, so that it can't be instantiated directly.

The default impl of some observers manages their own lifetime (e.g. deletes
themselves from some override). It makes sense to make the dtor protected in
those cases. But that's not the case here (or for the other observers you list).

[pkotwicz, 2015-02-24 21:18:03]

The CQ bit was checked by pkotwicz@chromium.org

[pkotwicz, 2015-02-24 21:18:03]

The patchset sent to the CQ was uploaded after l-g-t-m from sadrul@chromium.org
Link to the patchset: https://codereview.chromium.org/945983002/#ps40001 (title:
" ")

[commit-bot: I haz the power, 2015-02-24 21:18:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/945983002/40001

[commit-bot: I haz the power, 2015-02-24 22:47:01]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-24 22:47:33]

Patchset 3 (id:??) landed as
https://crrev.com/3a50bbb3427ce20ad60bc2966358081b529de76d
Cr-Commit-Position: refs/heads/master@{#317908}