Revert of Convert sticky keys to a chromeos::EventRewriter phase.

Revert of Convert sticky keys to a chromeos::EventRewriter phase. (https://codereview.chromium.org/255033003/)

Reason for revert:
http://build.chromium.org/p/chromium.memory.fyi/builders/Chromium%20OS%20%28valgrind%29%285%29/builds/27608/steps/memory%20test%3A%20unit/logs/stdio

The change to chromeos::EventRewriter::RewriteEvent() leads to a ui::MouseEvent object being used for a ui::MouseWheelEvent.

Original issue's description:
> Convert sticky keys to a chromeos::EventRewriter phase.
> 
> BUG=354035
> TEST=unit_tests,ash_unittests,manual
> R=sadrul@chromium.org,derat@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=278342

[kpschoedel, 2014-06-19 14:05:37]

Created Revert of Convert sticky keys to a chromeos::EventRewriter phase.

[commit-bot: I haz the power, 2014-06-19 14:06:27]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kpschoedel@chromium.org/343923002/1

[commit-bot: I haz the power, 2014-06-19 14:06:28]

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

[commit-bot: I haz the power, 2014-06-19 14:06:29]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Daniel Erat, 2014-06-19 14:09:28]

rubberstamp lgtm

[Daniel Erat, 2014-06-19 14:09:35]

The CQ bit was checked by derat@chromium.org

[commit-bot: I haz the power, 2014-06-19 14:11:05]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kpschoedel@chromium.org/343923002/1

[commit-bot: I haz the power, 2014-06-19 18:25:26]

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

[commit-bot: I haz the power, 2014-06-19 18:25:27]

Failed to apply patch for ash/shell.cc:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file ash/shell.cc
  Hunk #1 succeeded at 896 with fuzz 2 (offset 7 lines).
  Hunk #2 FAILED at 928.
  1 out of 2 hunks FAILED -- saving rejects to file ash/shell.cc.rej

Patch:       ash/shell.cc
Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index
2c393065aba614f7c7caa01fa365b5f490a2a9c8..c8b327979249e3eaabbad01a31fc24a65b6edf96
100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -889,6 +889,13 @@
 
   // The order in which event filters are added is significant.
 
+#if defined(OS_CHROMEOS)
+  // The StickyKeysController also rewrites events and must be added
+  // before observers, but after the EventRewriterEventFilter.
+  sticky_keys_controller_.reset(new StickyKeysController);
+  AddPreTargetHandler(sticky_keys_controller_.get());
+#endif
+
   // wm::UserActivityDetector passes events to observers, so let them get
   // rewritten first.
   user_activity_detector_.reset(new ::wm::UserActivityDetector);
@@ -921,10 +928,6 @@
   // created.
 #if defined(OS_CHROMEOS)
     keyboard::InitializeKeyboard();
-#endif
-
-#if defined(OS_CHROMEOS)
-  sticky_keys_controller_.reset(new StickyKeysController);
 #endif
 
   lock_state_controller_.reset(new LockStateController);