Increase the slop value for text selection offsets

Increase the slop value for text selection offsets

A small selection offset is used when a selection handle is dragged to
ensure the coordinate sent to the renderer is on the correct line of
text. Increase the 'slop' value of this offset to accomodate lines/fonts
with significant whitespace below the actual text visuals.

BUG=484479
Committed: https://crrev.com/efa4c8123c23646e6d3e5df65b60e76aa8ed59d8
Cr-Commit-Position: refs/heads/master@{#332522}

[jdduke (slow), 2015-05-05 19:02:51]

jdduke@chromium.org changed reviewers:
+ mohsen@chromium.org

[jdduke (slow), 2015-05-05 19:02:52]

mohsen@: PTAL. I thought of doing some more sophisticated handle re-anchoring,
but it doesn't work quite as well when the selection can span lines that have
drastically different text sizes (see issue 450640). Bumping the slop value here
seems to handle the most problematic cases.

[jdduke (slow), 2015-06-02 18:48:04]

Hmm, I've started noticing this issue more, and until we have a more permanent
fix for crbug.com/484479 what do you think about trying to land this? It's not a
perfect solution but it slightly eases the pain.

[mohsen, 2015-06-02 19:05:16]

On 2015/06/02 18:48:04, jdduke wrote:
> Hmm, I've started noticing this issue more, and until we have a more permanent
> fix for crbug.com/484479 what do you think about trying to land this? It's not
a
> perfect solution but it slightly eases the pain.

LGTM

[jdduke (slow), 2015-06-02 19:14:26]

The CQ bit was checked by jdduke@chromium.org

[jdduke (slow), 2015-06-02 19:14:26]

The patchset sent to the CQ was uploaded after l-g-t-m from mohsen@chromium.org
Link to the patchset: https://codereview.chromium.org/1129443006/#ps20001
(title: "Rebase")

[commit-bot: I haz the power, 2015-06-02 19:15:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1129443006/20001

[commit-bot: I haz the power, 2015-06-02 19:33:03]

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

[commit-bot: I haz the power, 2015-06-02 19:33:05]

Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[jdduke (slow), 2015-06-02 19:38:21]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2015-06-02 19:43:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1129443006/20001

[commit-bot: I haz the power, 2015-06-02 20:19:52]

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

[commit-bot: I haz the power, 2015-06-02 20:19:53]

Try jobs failed on following builders:
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[jdduke (slow), 2015-06-02 23:47:59]

The CQ bit was checked by jdduke@chromium.org

[jdduke (slow), 2015-06-02 23:48:00]

The patchset sent to the CQ was uploaded after l-g-t-m from mohsen@chromium.org
Link to the patchset: https://codereview.chromium.org/1129443006/#ps40001
(title: "Fix test")

[commit-bot: I haz the power, 2015-06-02 23:48:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1129443006/40001

[commit-bot: I haz the power, 2015-06-03 03:12:16]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-06-03 03:13:14]

Patchset 3 (id:??) landed as
https://crrev.com/efa4c8123c23646e6d3e5df65b60e76aa8ed59d8
Cr-Commit-Position: refs/heads/master@{#332522}