MacViews: Refactor ShowConfirmBubble to also take a gfx::NativeWindow

MacViews: Refactor ShowConfirmBubble to also take a gfx::NativeWindow

Currently there's a view/window type mismatch that Aura excuses because
they are the same type (aura::Window*). This doesn't work on MacViews.

For toolkit-views, CreateBrowserModalDialogViews(..) actually takes a
gfx::NativeWindow. However, for Cocoa, the confirm bubble is added as a
subview of the render view.

This changes chrome::ShowConfirmBubble() to accept both a NativeView and
a NativeWindow. Views ignores the view and Cocoa ignores the window but
it allows a toolkit-views build on Mac to call the Cocoa implementation
which is what we need to get started.

BUG=390755
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283373

[tapted, 2014-07-15 11:37:51]

msw: please review - the second call changes slightly, but I think this is the
right thing to do (r181975 for context).
lazyboy: please review for OWNERS in renderer_context_menu

Note that confirm_bubble_cocoa is suffering from some decay (
http://crbug.com/393887 )... this looks like one to prioritise replacing with a
views implementation. I started off with a more ambitious refactor in earlier
patchsets, but I got scared off. I think this is a reasonable alternative.

[lazyboy, 2014-07-15 19:08:34]

lgtm

render_view_context_menu/* LGTM

[msw, 2014-07-15 22:44:16]

lgtm

[tapted, 2014-07-15 22:46:15]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2014-07-15 22:50:22]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tapted@chromium.org/393763002/60001

[commit-bot: I haz the power, 2014-07-16 04:42:26]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)

[commit-bot: I haz the power, 2014-07-16 06:07:18]

Change committed as 283373