Run input_method_bridge_unittest on Mac, remove unused DummyInputMethodDelegate

Run input_method_bridge_unittest on Mac, remove unused DummyInputMethodDelegate

A recent refactor means that aura::client::kRootWindowInputMethodKey is
no longer used for the test. So, to run it on Mac, it's just a matter of
using the platform-independent types provided by WidgetTest.

After this CL, DummyInputMethodDelegate would be unused, so it is
deleted.

BUG=378134

[tapted, 2015-06-24 04:47:42]

tapted@chromium.org changed reviewers:
+ shuchen@google.com

[tapted, 2015-06-24 05:13:03]

tapted@chromium.org changed reviewers:
+ shuchen@chromium.org
- shuchen@google.com

[tapted, 2015-06-24 05:24:22]

shuchen: please take a look

Thanks!

https://codereview.chromium.org/1203023002/diff/20001/ui/views/ime/input_meth...
File ui/views/ime/input_method_bridge_unittest.cc (left):

https://codereview.chromium.org/1203023002/diff/20001/ui/views/ime/input_meth...
ui/views/ime/input_method_bridge_unittest.cc:21: ui::InputMethodMinimal
input_method(&input_method_delegate);
http://crrev.com/333698 removed a line below this that did 

  GetContext()->SetProperty(aura::client::kRootWindowInputMethodKey,	
                            static_cast<ui::InputMethod*>(&input_method));

with that gone, input_method (and the DummyInputMethodDelegate), are not used,
so I've removed them. Added a comment below about where things are owned.

There were no other users of DummyInputMethodDelegate.

[tapted, 2015-06-24 23:33:04]

shuchen: ping?

[Shu Chen, 2015-06-25 00:57:42]

On 2015/06/24 23:33:04, tapted wrote:
> shuchen: ping?

Sorry for late reply.

InputMethodBridge will soon be gone. Please see
https://codereview.chromium.org/1177503003.

[tapted, 2015-06-25 01:10:30]

On 2015/06/25 00:57:42, Shu Chen wrote:
> On 2015/06/24 23:33:04, tapted wrote:
> > shuchen: ping?
> 
> Sorry for late reply.
> 
> InputMethodBridge will soon be gone. Please see
> https://codereview.chromium.org/1177503003.

Nice!

I'll close this. Note you can probably also remove dummy_input_method_delegate.*
after https://codereview.chromium.org/1177503003 lands too.

[Shu Chen, 2015-06-25 01:15:57]

On 2015/06/25 01:10:30, tapted wrote:
> On 2015/06/25 00:57:42, Shu Chen wrote:
> > On 2015/06/24 23:33:04, tapted wrote:
> > > shuchen: ping?
> > 
> > Sorry for late reply.
> > 
> > InputMethodBridge will soon be gone. Please see
> > https://codereview.chromium.org/1177503003.
> 
> Nice!
> 
> I'll close this. Note you can probably also remove
dummy_input_method_delegate.*
> after https://codereview.chromium.org/1177503003 lands too.

Noted, thanks!