Fix a leak that only happens in layout test mode.

Fix a leak that only happens in layout test mode.

MockWebClipboardImpl is only used in layout test mode and it
contains some member variables.  Since the destructors weren't
virtual, it was leaking these member variables.

BUG=17184

[tony, 2009-07-22 22:53:40]

Question for Darin: Should all the abstract classes in webkit/api/public/*.h
have virtual destructors?  It doesn't look like most of them do.

[ojan, 2009-07-22 23:01:32]

LGTM

[darin (slow to review), 2009-07-22 23:11:43]

The expectation I had was that a WebClipboard subclass would never be deleted
via a base class pointer.  To be safe, I suppose we should add similar virtual
destructors to other interfaces in the WebKit API just in case the usage pattern
of the embedder would benefit from it (as in this case).

[dank, 2009-07-22 23:29:53]

-Wnon-virtual-dtor is a handy compiler option that warns
about this situation, should we start using it?

[darin (slow to review), 2009-07-22 23:50:31]

I think the issue is that this is WebKit code (well, it will be soon), and I
think WebKit intentionally avoids virtual destructors when they are not
needed.-Darin


On Wed, Jul 22, 2009 at 4:29 PM, <dank@chromium.org> wrote:

> -Wnon-virtual-dtor is a handy compiler option that warns
> about this situation, should we start using it?
>
>
>
> http://codereview.chromium.org/159238
>

[darin (slow to review), 2009-07-22 23:51:16]

See for instance:  https://bugs.webkit.org/show_bug.cgi?id=27563

On Wed, Jul 22, 2009 at 4:50 PM, Darin Fisher <darin@chromium.org> wrote:

> I think the issue is that this is WebKit code (well, it will be soon), and
> I think WebKit intentionally avoids virtual destructors when they are not
> needed.-Darin
>
>
> On Wed, Jul 22, 2009 at 4:29 PM, <dank@chromium.org> wrote:
>
>> -Wnon-virtual-dtor is a handy compiler option that warns
>> about this situation, should we start using it?
>>
>>
>>
>> http://codereview.chromium.org/159238
>>
>
>