Don't pass NCMOUSEMOVE to RenderWidgetHostViewAura

Don't pass NCMOUSEMOVE to RenderWidgetHostViewAura

On dispatching ET_EXITED, the event is sent with a native_event
of NCMOUSEMOVE, which the renderer doesn't want, so don't send
it on.

R=sky@chromium.org
BUG=173051
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=180016

[scottmg, 2013-01-31 19:29:32]

This fixes the crash, but I'm not sure if it's really the correct place to avoid
sending the message through to the renderer. WDYT?

context: https://code.google.com/p/chromium/issues/detail?id=173051#c3

[sky, 2013-01-31 21:05:45]

Any idea why we don't hit this on non-aura builds?

[scottmg, 2013-01-31 22:17:55]

On 2013/01/31 21:05:45, sky wrote:
> Any idea why we don't hit this on non-aura builds?

I don't really fully understand the difference between how event dispatch works
between aura and non-aura.

On non-aura, the event goes:
- HWNDMessageHandler -> NativeWidgetWin -> Widget -> RootView::OnMouseMoved.
There's mouse_move_handler_ in RootView and that's null when the NCMOUSEMOVE
comes in, so RootView doesn't forward the EXITED event anywhere.

On aura, the event goes:
- HWNDMessageHandler -> DesktopRootWindowHostWin -> RootWindow where then goes
back through the EventDispatcher. There's no handlers for the event, so it gets
sent to the default, which ends up being the RWHVA. It never goes through the
RootView, so the flow is quite different.

This change modifies RWHVA to ignore the NC events, but I'm not clear on if they
should have been filtered earlier or not, ideally.

[sky, 2013-01-31 22:44:18]

Ananta came over and described this to me. LGTM