Fix Linux Aura drag-and-drop cancellation.

Fix Linux Aura drag-and-drop cancellation.

Fixes Escape key drag-and-drop cancellation handling.
(this is a followup fix for Issue 344289 and r254289)

SendXdndLeave(source_current_window_) in OnMoveLoopEnded.
(seems like a misnomer, this is the target drop window)
(alerts the target window to repaint and cleanup, etc.)

BUG=349151, 344289
TEST=Dragging text, bookmarks, etc. from a Linux Aura browser window to the same window, other Chrome windows, and other application is cancelled correctly when pressing [Esc] (no lingering drop indicator, etc.).
R=erg@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=255449

[msw, 2014-03-06 03:14:45]

Hey Elliot and Scott, please take a look; thanks!

[sky, 2014-03-06 16:37:19]

You don't need me for this, erg is fine.
-sky

[msw, 2014-03-06 17:55:17]

Right on, please take a look Elliot, the solution was simpler than anticipated.

[Elliot Glaysher, 2014-03-06 18:05:31]

On 2014/03/06 17:55:17, msw wrote:
> Right on, please take a look Elliot, the solution was simpler than
anticipated.

That actually makes a bunch of sense. LGTM!

[msw, 2014-03-06 18:15:20]

The CQ bit was checked by msw@chromium.org

[commit-bot: I haz the power, 2014-03-06 18:16:16]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msw@chromium.org/181013011/70001

[commit-bot: I haz the power, 2014-03-06 20:54:45]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msw@chromium.org/181013011/70001

[commit-bot: I haz the power, 2014-03-06 21:42:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msw@chromium.org/181013011/70001

[commit-bot: I haz the power, 2014-03-06 22:17:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msw@chromium.org/181013011/70001

[commit-bot: I haz the power, 2014-03-06 22:29:39]

Change committed as 255449