Use EventHandler for IME

Use EventHandler for IME so that it honeres EventTargeter/EventHandlers.

This also moves the InputEventEventHandler to early stage. This is so that
KeyHoldDetectorss won't recieve events twice.

InputMethodEventHandler skips sending to IME when
* event was posted via DispatchKeyEventPostIME
* or event is synthesized. This is necessary
  for software keyboard. We can't simply rely on synthesized mask because there key_hold_detector also generates key event.

BUG=502113
Committed: https://crrev.com/5e0fff892917abdbbb1f8be7441c6b8179c83f40
Cr-Commit-Position: refs/heads/master@{#336487}

[oshima, 2015-06-24 17:58:40]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-24 18:00:42]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/1

[oshima, 2015-06-24 18:30:16]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-24 18:32:11]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/20001

[oshima, 2015-06-24 18:35:25]

Patchset #1 (id:1) has been deleted

[commit-bot: I haz the power, 2015-06-24 19:16:20]

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

[commit-bot: I haz the power, 2015-06-24 19:16:21]

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

[oshima, 2015-06-25 20:39:44]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-25 20:40:18]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/40001

[oshima, 2015-06-25 20:43:54]

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

[commit-bot: I haz the power, 2015-06-25 21:23:02]

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

[commit-bot: I haz the power, 2015-06-25 21:23:03]

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

[oshima, 2015-06-25 23:03:35]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[oshima, 2015-06-25 23:04:03]

The CQ bit was unchecked by oshima@chromium.org

[oshima, 2015-06-25 23:19:09]

Patchset #3 (id:60001) has been deleted

[oshima, 2015-06-25 23:19:21]

Patchset #2 (id:40001) has been deleted

[oshima, 2015-06-25 23:19:26]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-25 23:20:38]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/80001

[oshima, 2015-06-25 23:24:08]

I'd like to land this for 45. We can work on better solution after branch cut.

[oshima, 2015-06-25 23:26:32]

fyi: +shuchen, suzhe

[oshima, 2015-06-25 23:27:00]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-25 23:27:19]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/100001

[commit-bot: I haz the power, 2015-06-26 00:07:12]

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

[commit-bot: I haz the power, 2015-06-26 00:07:14]

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

[oshima, 2015-06-26 00:12:11]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-26 00:12:56]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/120001

[commit-bot: I haz the power, 2015-06-26 01:31:29]

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

[commit-bot: I haz the power, 2015-06-26 01:31:30]

Dry run: Exceeded global retry quota

[sadrul, 2015-06-26 15:58:49]

The windows trybot failures look relevant. Mind taking a look?

[James Su, 2015-06-26 16:33:58]

Two questions:

1. Besides IME itself, which components will generate key events with
EF_IS_SYNTHESIZED flag? E.g. does software keyboard generate synthesized key
events?
Please note that, key events generated by software keyboard should be sent to
IME for handling.

2. Is InputMethodEventHandler always the first handler receiving key events?
If not, then all event handers before InputMethodEventHandler will receive a key
event twice, if the event reaches IME.

I'm ok to land this CL as a temporary solution for M45, if you think Shu's CL
https://codereview.chromium.org/1209913002 is risky. But I strongly suggest that
we should find out a better unified solution for M46.

[oshima, 2015-06-26 19:33:57]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-26 19:34:40]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/140001

[oshima, 2015-06-26 19:47:38]

The CQ bit was checked by oshima@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-26 19:48:15]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/160001

[oshima, 2015-06-26 20:10:10]

On 2015/06/26 15:58:49, sadrul wrote:
> The windows trybot failures look relevant. Mind taking a look?

This was because I forgot to change ash_remote_window_tree_host_win. Uploaded
new patch. PTAL.

[commit-bot: I haz the power, 2015-06-26 20:44:41]

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

[commit-bot: I haz the power, 2015-06-26 20:44:42]

Dry run: This issue passed the CQ dry run.

[oshima, 2015-06-26 21:22:16]

On 2015/06/26 16:33:58, James Su wrote:
> Two questions:
> 
> 1. Besides IME itself, which components will generate key events with
> EF_IS_SYNTHESIZED flag? E.g. does software keyboard generate synthesized key
> events?
> Please note that, key events generated by software keyboard should be sent to
> IME for handling.

KeyHoldDetector may generate synthesized key event.

> 
> 2. Is InputMethodEventHandler always the first handler receiving key events?
> If not, then all event handers before InputMethodEventHandler will receive a
key
> event twice, if the event reaches IME.

No, and I do understand this behavior. I moved the InputMethodEventHandler to
make
sure this won't cause the issue.
 
> I'm ok to land this CL as a temporary solution for M45, if you think Shu's CL
> https://codereview.chromium.org/1209913002 is risky. But I strongly suggest
that
> we should find out a better unified solution for M46.

Agreed. This is just for 45. Let's file a new bug and continue the discussion
there.

[sadrul, 2015-06-27 01:23:52]

lgtm for now. We should revisit for a better fix.

[oshima, 2015-06-27 01:26:25]

The CQ bit was checked by oshima@chromium.org

[commit-bot: I haz the power, 2015-06-27 01:26:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209663002/160001

[commit-bot: I haz the power, 2015-06-27 01:31:40]

Committed patchset #6 (id:160001)

[commit-bot: I haz the power, 2015-06-27 01:32:33]

Patchset 6 (id:??) landed as
https://crrev.com/5e0fff892917abdbbb1f8be7441c6b8179c83f40
Cr-Commit-Position: refs/heads/master@{#336487}