gfx: Remove gfx::NativeEditView.

gfx: Remove gfx::NativeEditView.

There is only one use left for NativeEditView for content-shell on mac. So
remove the NativeEditView typedef on all platforms, and instead explicitly use
NSTextField for content-shell on mac.

BUG=500004
Committed: https://crrev.com/8b11d2650f933e26dda39f6e8832c986056f5eef
Cr-Commit-Position: refs/heads/master@{#359337}

[sadrul, 2015-11-12 01:31:03]

sadrul@chromium.org changed reviewers:
+ peter@chromium.org

[Peter Beverloo, 2015-11-12 14:03:42]

lgtm

[sadrul, 2015-11-12 18:14:58]

The CQ bit was checked by sadrul@chromium.org

[commit-bot: I haz the power, 2015-11-12 18:16:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1440683003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1440683003/1

[commit-bot: I haz the power, 2015-11-12 18:41:43]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-12 20:08:12]

Patchset 1 (id:??) landed as
https://crrev.com/8b11d2650f933e26dda39f6e8832c986056f5eef
Cr-Commit-Position: refs/heads/master@{#359337}