Work around PanGestureRecognizer iOS10 issue.

Work around PanGestureRecognizer iOS10 issue.

In iOS10, sometimes a PanGestureRecognizer will fire a touchesMoved even
after touchesBegan sets its state to |UIGestureRecognizerStateFailed|.
Somehow the state is re-set to UIGestureRecognizerStatePossible, and ends
up in moved.  Checking if |_startPoint| has been set is a secondary way to
catch for failed gestures. It appears setting failed in touchesMoved still always
works -- this issue only seems to be related to setting Failure in touchesBegan,
and only sometimes.

BUG=640611
Committed: https://crrev.com/95144337ab1af223377554b7ca838de787d8080e
Cr-Commit-Position: refs/heads/master@{#415004}

[justincohen, 2016-08-26 21:49:08]

justincohen@chromium.org changed reviewers:
+ rohitrao@chromium.org

[justincohen, 2016-08-26 21:49:08]

Thoughts?

[rohitrao (ping after 24h), 2016-08-29 13:30:22]

lgtm

[rohitrao (ping after 24h), 2016-08-29 13:31:46]

This seems pretty safe for M53.

[justincohen, 2016-08-29 13:34:03]

Description was changed from

==========
Work around PanGestureRecognizer iOS10 issue.

In iOS10, sometimes a PanGestureRecognizer will fire a touchesMoved even
after touchesBegan sets its state to |UIGestureRecognizerStateFailed|.
Somehow the state is re-set to UIGestureRecognizerStatePossible, and ends
up in moved.  Checking if |_startPoint| has been set is a secondary way to
catch for failed gestures.

BUG=
==========

to

==========
Work around PanGestureRecognizer iOS10 issue.

In iOS10, sometimes a PanGestureRecognizer will fire a touchesMoved even
after touchesBegan sets its state to |UIGestureRecognizerStateFailed|.
Somehow the state is re-set to UIGestureRecognizerStatePossible, and ends
up in moved.  Checking if |_startPoint| has been set is a secondary way to
catch for failed gestures. It appears setting failed in touchesMoved still
always
works -- this issue only seems to be related to setting Failure in touchesBegan,

and only sometimes. 

BUG=640611
==========

[justincohen, 2016-08-29 13:34:07]

The CQ bit was checked by justincohen@chromium.org

[commit-bot: I haz the power, 2016-08-29 13:34:22]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-29 14:10:41]

Description was changed from

==========
Work around PanGestureRecognizer iOS10 issue.

In iOS10, sometimes a PanGestureRecognizer will fire a touchesMoved even
after touchesBegan sets its state to |UIGestureRecognizerStateFailed|.
Somehow the state is re-set to UIGestureRecognizerStatePossible, and ends
up in moved.  Checking if |_startPoint| has been set is a secondary way to
catch for failed gestures. It appears setting failed in touchesMoved still
always
works -- this issue only seems to be related to setting Failure in touchesBegan,

and only sometimes. 

BUG=640611
==========

to

==========
Work around PanGestureRecognizer iOS10 issue.

In iOS10, sometimes a PanGestureRecognizer will fire a touchesMoved even
after touchesBegan sets its state to |UIGestureRecognizerStateFailed|.
Somehow the state is re-set to UIGestureRecognizerStatePossible, and ends
up in moved.  Checking if |_startPoint| has been set is a secondary way to
catch for failed gestures. It appears setting failed in touchesMoved still
always
works -- this issue only seems to be related to setting Failure in touchesBegan,

and only sometimes. 

BUG=640611
==========

[commit-bot: I haz the power, 2016-08-29 14:10:42]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-29 14:12:22]

Description was changed from

==========
Work around PanGestureRecognizer iOS10 issue.

In iOS10, sometimes a PanGestureRecognizer will fire a touchesMoved even
after touchesBegan sets its state to |UIGestureRecognizerStateFailed|.
Somehow the state is re-set to UIGestureRecognizerStatePossible, and ends
up in moved.  Checking if |_startPoint| has been set is a secondary way to
catch for failed gestures. It appears setting failed in touchesMoved still
always
works -- this issue only seems to be related to setting Failure in touchesBegan,

and only sometimes. 

BUG=640611
==========

to

==========
Work around PanGestureRecognizer iOS10 issue.

In iOS10, sometimes a PanGestureRecognizer will fire a touchesMoved even
after touchesBegan sets its state to |UIGestureRecognizerStateFailed|.
Somehow the state is re-set to UIGestureRecognizerStatePossible, and ends
up in moved.  Checking if |_startPoint| has been set is a secondary way to
catch for failed gestures. It appears setting failed in touchesMoved still
always
works -- this issue only seems to be related to setting Failure in touchesBegan,
and only sometimes.

BUG=640611

Committed: https://crrev.com/95144337ab1af223377554b7ca838de787d8080e
Cr-Commit-Position: refs/heads/master@{#415004}
==========

[commit-bot: I haz the power, 2016-08-29 14:12:23]

Patchset 1 (id:??) landed as
https://crrev.com/95144337ab1af223377554b7ca838de787d8080e
Cr-Commit-Position: refs/heads/master@{#415004}