Mac: Don't allow history swiping after substantial vertical motion.

Mac: Don't allow history swiping after substantial vertical motion.

Previously, the logic for history swiping depended on the relative Y distance
of the gesture's current location from the gesture's start location. Gestures
which consisted of a large up motion, followed by a large down motion, followed
by a horizontal motion could still cause history swiping. The new logic depends
on the total Y distance of the gesture, which fixes this problem.

This CL also includes a change to allowed the gesture recognizer state machine
to enter the state kCancelled directly from the state kPending. Previously, it
was possible for the history overlay to show for a very brief period of time
even if the gesture was about to be cancelled.

This CL also includes a minor refactor:
 - Renamed several methods to better reflect their intended purpose.
 - Removed lastProcessedGestureId_ and currentGestureId_, which did not cause a
 functional change.

BUG=421629
Committed: https://crrev.com/bedaa557ad182057363cfe43140935e2a30cb63e
Cr-Commit-Position: refs/heads/master@{#300199}

[erikchen, 2014-10-16 20:39:24]

Patchset #1 (id:1) has been deleted

[erikchen, 2014-10-16 20:39:34]

Patchset #1 (id:20001) has been deleted

[erikchen, 2014-10-16 20:39:45]

erikchen@chromium.org changed reviewers:
+ avi@chromium.org

[erikchen, 2014-10-16 20:39:46]

avi: Please review.

[Avi (use Gerrit), 2014-10-17 19:53:55]

lgtm

[erikchen, 2014-10-17 20:55:32]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2014-10-17 20:57:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/657323003/40001

[commit-bot: I haz the power, 2014-10-17 21:06:07]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-17 21:06:09]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[erikchen, 2014-10-17 23:28:01]

erikchen@chromium.org changed reviewers:
+ thestig@chromium.org

[erikchen, 2014-10-17 23:28:01]

thestig: Please review.

[Lei Zhang, 2014-10-17 23:56:11]

lgtm stamp

https://codereview.chromium.org/657323003/diff/40001/chrome/browser/renderer_...
File
chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper_unit_test.mm
(right):

https://codereview.chromium.org/657323003/diff/40001/chrome/browser/renderer_...
chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper_unit_test.mm:284:
EXPECT_EQ(begin_count_, 0);
preferably EXPECT_EQ(expected_, actual), but there seems to be much momentum in
the other direction here. So consistency wins.

[erikchen, 2014-10-18 00:19:42]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2014-10-18 00:21:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/657323003/40001

[commit-bot: I haz the power, 2014-10-18 01:48:28]

Committed patchset #1 (id:40001)

[commit-bot: I haz the power, 2014-10-18 01:49:14]

Patchset 1 (id:??) landed as
https://crrev.com/bedaa557ad182057363cfe43140935e2a30cb63e
Cr-Commit-Position: refs/heads/master@{#300199}