Remove some probably dead code in EventHandler::handleDrag.

Remove some probably dead code in EventHandler::handleDrag.

This may have been used for AppKit integration at some point in the
distant past. Two checks for the left mouse button have been moved
up a bit higher and combined, since drags cannot be triggered by
any other button.

BUG=none

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=185389

[dcheng, 2014-11-14 01:48:04]

dcheng@chromium.org changed reviewers:
+ rbyers@chromium.org

[dcheng, 2014-11-14 01:48:17]

One more minor cleanup.

[Rick Byers, 2014-11-14 18:29:29]

https://codereview.chromium.org/726703002/diff/20001/Source/core/page/EventHa...
File Source/core/page/EventHandler.cpp (right):

https://codereview.chromium.org/726703002/diff/20001/Source/core/page/EventHa...
Source/core/page/EventHandler.cpp:653: if (!m_mousePressed ||
event.event().button() != LeftButton)
You said this case is "probably dead".  Should we perhaps add an ASSERT to see
if we can catch anyone trying to do a drag without the left button being
pressed?  If there are any such cases, it could be a compat bug...

[dcheng, 2014-11-14 18:41:26]

https://codereview.chromium.org/726703002/diff/20001/Source/core/page/EventHa...
File Source/core/page/EventHandler.cpp (right):

https://codereview.chromium.org/726703002/diff/20001/Source/core/page/EventHa...
Source/core/page/EventHandler.cpp:653: if (!m_mousePressed ||
event.event().button() != LeftButton)
On 2014/11/14 18:29:28, Rick Byers wrote:
> You said this case is "probably dead".  Should we perhaps add an ASSERT to see
> if we can catch anyone trying to do a drag without the left button being
> pressed?  If there are any such cases, it could be a compat bug...

The thing is, we always bailed out anyway if it wasn't a left button drag. The
check was just done in two different places before--once at the beginning
handleDrag(), and once after handleDrag() returned. The check has been
consolidated into one place.

The other possibility is someone passing in a MouseEvent that's not a MouseMoved
event. In that case, we would skip the HTML drag steps, but not skip the default
drag handling steps. It seems a bit silly to do that, so now, we go through the
same set of steps for both.

[Rick Byers, 2014-11-14 18:56:20]

On 2014/11/14 18:41:26, dcheng wrote:
>
https://codereview.chromium.org/726703002/diff/20001/Source/core/page/EventHa...
> File Source/core/page/EventHandler.cpp (right):
> 
>
https://codereview.chromium.org/726703002/diff/20001/Source/core/page/EventHa...
> Source/core/page/EventHandler.cpp:653: if (!m_mousePressed ||
> event.event().button() != LeftButton)
> On 2014/11/14 18:29:28, Rick Byers wrote:
> > You said this case is "probably dead".  Should we perhaps add an ASSERT to
see
> > if we can catch anyone trying to do a drag without the left button being
> > pressed?  If there are any such cases, it could be a compat bug...
> 
> The thing is, we always bailed out anyway if it wasn't a left button drag. The
> check was just done in two different places before--once at the beginning
> handleDrag(), and once after handleDrag() returned. The check has been
> consolidated into one place.
> 
> The other possibility is someone passing in a MouseEvent that's not a
MouseMoved
> event. In that case, we would skip the HTML drag steps, but not skip the
default
> drag handling steps. It seems a bit silly to do that, so now, we go through
the
> same set of steps for both.

Ok, thanks for the details.  LGTM.

[dcheng, 2014-11-14 19:11:26]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2014-11-14 19:12:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/726703002/20001

[commit-bot: I haz the power, 2014-11-14 19:57:48]

Committed patchset #2 (id:20001) as 185389